TY - JOUR A1 - Melnick, Daniel A1 - Charlet, Francois A1 - Echtler, Helmut P. A1 - De Batist, Marc T1 - Incipient axial collapse of the Main Cordillera and strain partitioning gradient between the central and Patagonian Andes, Lago Laja, Chile JF - Tectonics N2 - Lago Laja is a late Quaternary volcanic‐dammed lake located near the drainage divide of the south central Andes. Field observations, lake reflection seismic profiles, bathymetry, and remote sensing data reveal an active fault system that runs parallel to the volcanic arc along the axis of the Main Cordillera, the Lago Laja fault system (LLFS). Normal faults of this extensional system cut late Pleistocene volcanics, <7.1 ka still water lacustrine sediments, 6.3 ka pyroclastic deposits, and Holocene alluvial fans. We divide the LLFS in three segments on the basis of fault geometry, width, and slip magnitude. The underwater faults of the central segment in the lake's deepest part have the maximum Holocene vertical slip rate of >2.7 mm/yr. Since 7.1 ka, the LLFS accounts for ∼0.7% of arc‐normal extension at an average minimum rate of 1.2 mm/yr and strain rate of ∼10−14 s−1. Seismites and surface ruptures evidence M>6 paleoearthquakes. The Main Cordillera at ∼37°S is a large‐scale pop‐up structure uplifted by thrusting along its foothills. In this light, we interpret extension in the axial and highest part of the Andes as incipient synorogenic gravitational collapse in response to uplift and crustal thickening. Thermal weakening due to elevated heat flow and postglacial lithospheric rebound and unbending have probably contributed to the arc‐limited collapse and Holocene acceleration of deformation rates. The lack of significant strike‐slip offsets along the LLFS as well as along both foothills‐thrust systems at 37°S contrasts with the intra‐arc dextral fault zone south of 38°S. Regional structural data indicates that north of 38°S, diffusely distributed strain reflects low partitioning of oblique subduction, while to the south deformation is localized in a discrete strike‐slip fault zone along the volcanic arc, reflecting a higher degree of partitioning. We relate this strain partitioning gradient to favorable fault orientations in the fore arc north of the Arauco Peninsula, a major seismotectonic boundary. Y1 - 2006 U6 - https://doi.org/10.1029/2005TC001918 SN - 0278-7407 VL - 25 IS - 5 PB - Union CY - Washington ER - TY - JOUR A1 - Melnick, Daniel A1 - Li, Shaoyang A1 - Moreno, Marcos A1 - Cisternas, Marco A1 - Jara-Munoz, Julius A1 - Wesson, Robert A1 - Nelson, Alan A1 - Baez, Juan Carlos A1 - Deng, Zhiguo T1 - Back to full interseismic plate locking decades after the giant 1960 Chile earthquake JF - Nature Communications N2 - Great megathrust earthquakes arise from the sudden release of energy accumulated during centuries of interseismic plate convergence. The moment deficit (energy available for future earthquakes) is commonly inferred by integrating the rate of interseismic plate locking over the time since the previous great earthquake. But accurate integration requires knowledge of how interseismic plate locking changes decades after earthquakes, measurements not available for most great earthquakes. Here we reconstruct the post-earthquake history of plate locking at Guafo Island, above the seismogenic zone of the giant 1960 (M-w = 9.5) Chile earthquake, through forward modeling of land-level changes inferred from aerial imagery (since 1974) and measured by GPS (since 1994). We find that interseismic locking increased to similar to 70% in the decade following the 1960 earthquake and then gradually to 100% by 2005. Our findings illustrate the transient evolution of plate locking in Chile, and suggest a similarly complex evolution elsewhere, with implications for the time- and magnitude-dependent probability of future events. Y1 - 2018 U6 - https://doi.org/10.1038/s41467-018-05989-6 SN - 2041-1723 VL - 9 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Li, Shaoyang A1 - Moreno Switt, Marcos A1 - Bedford, Jonathan A1 - Rosenau, Matthias A1 - Heidbach, Oliver A1 - Melnick, Daniel A1 - Oncken, Onno T1 - Postseismic uplift of the Andes following the 2010 Maule earthquake BT - Implications for mantle rheology JF - Geophysical research letters N2 - Postseismic surface deformation associated with great subduction earthquakes is controlled by asthenosphere rheology, frictional properties of the fault, and structural complexity. Here by modeling GPS displacements in the 6 years following the 2010 M-w 8.8 Maule earthquake in Chile, we investigate the impact of heterogeneous viscosity distribution in the South American subcontinental asthenosphere on the 3-D postseismic deformation pattern. The observed postseismic deformation is characterized by flexure of the South America plate with peak uplift in the Andean mountain range and subsidence in the hinterland. We find that, at the time scale of observation, over 2 orders of magnitude gradual increase in asthenosphere viscosity from the arc area toward the cratonic hinterland is needed to jointly explain horizontal and vertical displacements. Our findings present an efficient method to estimate spatial variations of viscosity, which clearly improves the fitting to the vertical signal of deformation. Lateral changes in asthenosphere viscosity can be correlated with the thermomechanical transition from weak subvolcanic arc mantle to strong subcratonic mantle, thus suggesting a stationary heterogeneous viscosity structure. However, we cannot rule out a transient viscosity structure (e.g., power law rheology) with the short time span of observation. Y1 - 2017 U6 - https://doi.org/10.1002/2016GL071995 SN - 0094-8276 SN - 1944-8007 VL - 44 IS - 4 SP - 1768 EP - 1776 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Melnick, Daniel A1 - Moreno, Marcos A1 - Quinteros, Javier A1 - Carlos Baez, Juan A1 - Deng, Zhiguo A1 - Li, Shaoyang A1 - Oncken, Onno T1 - The super-interseismic phase of the megathrust earthquake cycle in Chile JF - Geophysical research letters N2 - Along a subduction zone, great megathrust earthquakes recur either after long seismic gaps lasting several decades to centuries or over much shorter periods lasting hours to a few years when cascading successions of earthquakes rupture nearby segments of the fault. We analyze a decade of continuous Global Positioning System observations along the South American continent to estimate changes in deformation rates between the 2010 Maule (M8.8) and 2015 Illapel (M8.3) Chilean earthquakes. We find that surface velocities increased after the 2010 earthquake, in response to continental-scale viscoelastic mantle relaxation and to regional-scale increased degree of interplate locking. We propose that increased locking occurs transiently during a super-interseismic phase in segments adjacent to a megathrust rupture, responding to bending of both plates caused by coseismic slip and subsequent afterslip. Enhanced strain rates during a super-interseismic phase may therefore bring a megathrust segment closer to failure and possibly triggered the 2015 event. KW - megathrust KW - earthquake KW - cycle KW - Chile Y1 - 2017 U6 - https://doi.org/10.1002/2016GL071845 SN - 0094-8276 SN - 1944-8007 VL - 44 IS - 2 SP - 784 EP - 791 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - de Gelder, Gino A1 - Fernandez-Blanco, David A1 - Melnick, Daniel A1 - Duclaux, Guillaume A1 - Bell, Rebecca E. A1 - Jara-Munoz, Julius A1 - Armijo, Rolando A1 - Lacassin, Robin T1 - Lithospheric flexure and rheology determined by climate cycle markers in the Corinth Rift JF - Scientific reports N2 - Geomorphic strain markers accumulating the effects of many earthquake cycles help to constrain the mechanical behaviour of continental rift systems as well as the related seismic hazards. In the Corinth Rift (Greece), the unique record of onshore and offshore markers of Pleistocene similar to 100-ka climate cycles provides an outstanding possibility to constrain rift mechanics over a range of timescales. Here we use high-resolution topography to analyse the 3D geometry of a sequence of Pleistocene emerged marine terraces associated with flexural rift-flank uplift. We integrate this onshore dataset with offshore seismic data to provide a synoptic view of the flexural deformation across the rift. This allows us to derive an average slip rate of 4.5-9.0 mm.yr(-1) on the master fault over the past similar to 610 ka and an uplift/ subsidence ratio of 1:1.1-2.4. We reproduce the observed flexure patterns, using 3 and 5-layered lithospheric scale finite element models. Modelling results imply that the observed elastic flexure is produced by coseismic slip along 40-60 degrees planar normal faults in the elastic upper crust, followed by postseismic viscous relaxation occurring within the basal lower crust or upper mantle. We suggest that such a mechanism may typify rapid localised extension of continental lithosphere. Y1 - 2019 U6 - https://doi.org/10.1038/s41598-018-36377-1 SN - 2045-2322 VL - 9 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Moreno, Marcelo Spegiorin A1 - Bolte, John A1 - Klotz, Jan A1 - Melnick, Daniel T1 - Impact of megathrust geometry on inversion of coseismic slip from geodetic data : application to the 1960 Chile earthquake N2 - We analyze the role of megathrust geometry on slip estimation using the 1960 Chile earthquake (M-W = 9.5) as an example. A variable slip distribution for this earthquake has been derived by Barrientos and Ward (1990) applying an elastic dislocation model with a planar fault geometry. Their model shows slip patches at 80-110 km depth, isolated from the seismogenic zone, interpreted as aseismic slip. We invert the same geodetic data set using a finite element model (FEM) with precise geometry derived from geophysical data. Isoparametric FEM is implemented to constrain the slip distribution of curve-shaped elements. Slip resolved by our precise geometry model is limited to the shallow region of the plate interface suggesting that the deep patches of moment were most likely an artifact of the planar geometry. Our study emphasizes the importance of fault geometry on slip estimation of large earthquakes. Y1 - 2009 UR - http://www.agu.org/journals/gl/ U6 - https://doi.org/10.1029/2009gl039276 SN - 0094-8276 ER - TY - JOUR A1 - Farïas, Marcelo A1 - Vargas, Gabriel A1 - Tassara, Andrés A1 - Carretier, Sébastien A1 - Baize, Stéphane A1 - Melnick, Daniel A1 - Bataille, Klaus T1 - Land-level changes produced by the M-w 8.8 2010 Chilean earthquake N2 - We observed vertically displaced coastal and river markers after the 27 February 2010 Chilean earthquake [moment magnitude (Mw) 8.8]. Land-level changes range between 2.5 and -1 meters, evident along an ~500-kilometers- long segment identified here as the maximum length of coseismic rupture. A hinge line located 120 kilometers from the trench separates uplifted areas, to the west, from subsided regions. A simple elastic dislocation model fits these observations well; model parameters give a similar seismic moment to seismological estimates and suggest that most of the plate convergence since the 1835 great earthquake was elastically stored and then released during this event. Y1 - 2010 UR - http://www.sciencemag.org/ U6 - https://doi.org/10.1126/science.1192094 SN - 0036-8075 ER - TY - INPR A1 - Melnick, Daniel A1 - Moreno, Marcos A1 - Motagh, Mahdi A1 - Cisternas, Marco A1 - Wesson, Robert L. T1 - Splay fault slip during the M-w 8.8 2010 maule Chile earthquake reply T2 - Geology Y1 - 2013 U6 - https://doi.org/10.1130/G34825Y.1 SN - 0091-7613 SN - 1943-2682 VL - 41 IS - 12 SP - E310 EP - E310 PB - American Institute of Physics CY - Boulder ER - TY - JOUR A1 - Moreno, Marcelo Spegiorin A1 - Melnick, Daniel A1 - Rosenau, M. A1 - Báez, Juan Carlos A1 - Klotz, Jan A1 - Oncken, Onno A1 - Tassara, Andres A1 - Chen, J. A1 - Bataille, Klaus A1 - Bevis, M. A1 - Socquet, Anne A1 - Bolte, John A1 - Vigny, C. A1 - Brooks, B. A1 - Ryder, I. A1 - Grund, Volker A1 - Smalley, B. A1 - Carrizo, Daniel A1 - Bartsch, M. A1 - Hase, H. T1 - Toward understanding tectonic control on the M-w 8.8 2010 Maule Chile earthquake JF - Earth & planetary science letters N2 - The Maule earthquake of 27th February 2010 (M-w = 8.8) affected similar to 500 km of the Nazca-South America plate boundary in south-central Chile producing spectacular crustal deformation. Here, we present a detailed estimate of static coseismic surface offsets as measured by survey and continuous GPS, both in near- and far-field regions. Earthquake slip along the megathrust has been inferred from a Joint inversion of our new data together with published GPS, InSAR, and land-level changes data using Green's functions generated by a spherical finite-element model with realistic subduction zone geometry. The combination of the data sets provided a good resolution, indicating that most of the slip was well resolved. Coseismic slip was concentrated north of the epicenter with up to 16 m of slip, whereas to the south it reached over 10 m within two minor patches. A comparison of coseismic slip with the slip deficit accumulated since the last great earthquake in 1835 suggests that the 2010 event closed a mature seismic gap. Slip deficit distribution shows an apparent local overshoot that highlight cycle-to-cycle variability, which has to be taken into account when anticipating future events from interseismic observations. Rupture propagation was obviously not affected by bathymetric features of the incoming plate. Instead, splay faults in the upper plate seem to have limited rupture propagation in the updip and along-strike directions. Additionally, we found that along-strike gradients in slip are spatially correlated with geometrical inflections of the megathrust. Our study suggests that persistent tectonic features may control strain accumulation and release along subduction megathrusts. KW - GPS KW - Chile KW - Maule KW - slip model KW - FEM Y1 - 2012 U6 - https://doi.org/10.1016/j.epsl.2012.01.006 SN - 0012-821X VL - 321 IS - 3 SP - 152 EP - 165 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Melnick, Daniel A1 - Moreno, Marcos A1 - Motagh, Mahdi A1 - Cisternas, Marco A1 - Wesson, Robert L. T1 - Splay fault slip during the M-w 8.8 2010 Maule Chile earthquake JF - Geology N2 - Splay faults are thrusts that emerge from the plate boundaries of subduction zones. Such structures have been mapped at several convergent margins and their activity commonly ascribed to large megathrust earthquakes. However, the behavior of splay faults during the earthquake cycle is poorly constrained because typically these structures are located offshore and are difficult to access. Here we use geologic mapping combined with space and land geodesy, as well as offshore sonar data, to document surface-fault ruptures and coastal uplift at Isla Santa Maria in south-central Chile (37 degrees S) caused by the 27 February 2010 Maule earthquake (M-w 8.8). During the earthquake, the island was tilted parallel to the margin, and normal faults ruptured the surface and adjacent ocean bottom. We associate tilt and crestal normal faulting with growth of an anticline above a blind reverse fault rooted in the Nazca-South America plate boundary, which slipped during the Maule earthquake. The splay fault system has formed in an area of reduced coseismic plate-boundary slip, suggesting that anelastic deformation in the upper plate may have restrained the 2010 megathrust rupture. Surface fault breaks were accompanied by prominent discharge of fluids. Our field observations support the notion that splay faulting may frequently complement and influence the rupture of subduction-zone earthquakes. Y1 - 2012 U6 - https://doi.org/10.1130/G32712.1 SN - 0091-7613 VL - 40 IS - 3 SP - 251 EP - 254 PB - American Institute of Physics CY - Boulder ER - TY - JOUR A1 - Moreno, Marcelo Spegiorin A1 - Melnick, Daniel A1 - Rosenau, M. A1 - Bolte, John A1 - Klotz, Jan A1 - Echtler, Helmut Peter A1 - Báez, Juan Carlos A1 - Bataille, Klaus A1 - Chen, J. A1 - Bevis, M. A1 - Hase, H. A1 - Oncken, Onno T1 - Heterogeneous plate locking in the South-Central Chile subduction zone building up the next great earthquake JF - Earth & planetary science letters N2 - We use Global Positioning System (GPS) velocities and kinematic Finite Element models (FE-models) to infer the state of locking between the converging Nazca and South America plates in South-Central Chile (36 degrees S -46 degrees S) and to evaluate its spatial and temporal variability. GPS velocities provide information on earthquake-cycle deformation over the last decade in areas affected by the megathrust events of 1960 (M-w = 9.5) and 2010 (M-w = 8.8). Our data confirm that a change in surface velocity patterns of these two seismotectonic segments can be related to their different stages in the seismic cycle: Accordingly, the northern (2010) segment was in a final stage of interseismic loading whereas the southern (1960) segment is still in a postseismic stage and undergoes a prolonged viscoelastic mantle relaxation. After correcting the signals for mantle relaxation, the residual GPS velocity pattern suggests that the plate interface accumulates slip deficit in a spatially and presumably temporally variable way towards the next great event. Though some similarity exist between locking and 1960 coseismic slip, extrapolating the current, decadal scale slip deficit accumulation towards the similar to 300-yr recurrence times of giant events here does neither yield the slip distribution nor the moment magnitude of the 1960 earthquake. This suggests that either the locking pattern is evolving in time (to reconcile a slip deficit distribution similar to the 1960 earthquake) or that some asperities are not persistent over multiple events. The accumulated moment deficit since 1960 suggests that highly locked patches in the 1960 segment are already capable of producing a M similar to 8 event if triggered to fail by stress transfer from the 2010 event. KW - GPS KW - Chile KW - Maule KW - locking degree KW - postseismic deformation KW - earthquake cycle Y1 - 2011 U6 - https://doi.org/10.1016/j.epsl.2011.03.025 SN - 0012-821X VL - 305 IS - 3-4 SP - 413 EP - 424 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Li, Shaoyang A1 - Moreno, Marcos A1 - Rosenau, Matthias A1 - Melnick, Daniel A1 - Oncken, Onno T1 - Splay fault triggering by great subduction earthquakes inferred from finite element models JF - Geophysical research letters N2 - We have investigated the influence that megathrust earthquake slip has on the activation of splay faults using a 2-D finite element method (FEM), taking into account the effects of gravity and variations in the frictional strength properties of splay faults. We simulated both landward-dipping and seaward-dipping splay fault geometries, and imposed depth-variable slip distributions of subduction events. Our results indicate that the two types of splay fault exhibit a similar behavior, with variations in frictional properties along the faults affecting only the seismic magnitude. The triggering process is controlled by a critical depth. Megathrust slip concentrated at depths shallower than the critical depth will favor normal displacement, while megathrust slip concentrated at depths deeper than the critical depth is likely to result in reverse motion. Our results thus provide a useful tool for predicting the activation of secondary faults and may have direct implications for tsunami hazard research. KW - earthquake deformation KW - subduction zone earthquakes KW - splay faults KW - faulting behavior KW - FEM models KW - tsunami hazards Y1 - 2014 U6 - https://doi.org/10.1002/2013GL058598 SN - 0094-8276 SN - 1944-8007 VL - 41 IS - 2 SP - 385 EP - 391 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Wesson, Robert L. A1 - Melnick, Daniel A1 - Cisternas, Marco A1 - Moreno, Marcos A1 - Ely, Lisa L. T1 - Vertical deformation through a complete seismic cycle at Isla Santa Maria, Chile JF - Nature geoscience N2 - Individual great earthquakes are posited to release the elastic strain energy that has accumulated over centuries by the gradual movement of tectonic plates(1,2). However, knowledge of plate deformation during a complete seismic cycle-two successive great earthquakes and the intervening interseismic period-remains incomplete(3). A complete seismic cycle began in south-central Chile in 1835 with an earthquake of about magnitude 8.5 (refs 4,5) and ended in 2010 with a magnitude 8.8 earthquake(6). During the first earthquake, an uplift of Isla Santa Maria by 2.4 to 3m was documented(4,5). In the second earthquake, the island was uplifted(7) by 1.8 m. Here we use nautical surveys made in 1804, after the earthquake in 1835 and in 1886, together with modern echo sounder surveys and GPS measurements made immediately before and after the 2010 earthquake, to quantify vertical deformation through the complete seismic cycle. We find that in the period between the two earthquakes, Isla Santa Maria subsided by about 1.4 m. We simulate the patterns of vertical deformation with a finite-element model and find that they agree broadly with predictions from elastic rebound theory(2). However, comparison with geomorphic and geologic records of millennial coastline emergence(8,9) reveal that 10-20% of the vertical uplift could be permanent. Y1 - 2015 U6 - https://doi.org/10.1038/NGEO2468 SN - 1752-0894 SN - 1752-0908 VL - 8 IS - 7 SP - 547 EP - U157 PB - Nature Publ. Group CY - New York ER - TY - JOUR A1 - Jaramillo, Eduardo A1 - Dugan, Jenifer E. A1 - Hubbard, David M. A1 - Melnick, Daniel A1 - Manzano, Mario A1 - Duarte, Cristian A1 - Campos, Cesar A1 - Sanchez, Roland T1 - Ecological implications of extreme events footprints of the 2010earthquake along the chilean coast JF - PLoS one N2 - Deciphering ecological effects of major catastrophic events such as earthquakes, tsunamis, volcanic eruptions, storms and fires, requires rapid interdisciplinary efforts often hampered by a lack of pre-event data. Using results of intertidal surveys conducted shortly before and immediately after Chile's 2010 M-w 8.8 earthquake along the entire rupture zone (ca. 34-38 degrees S), we provide the first quantification of earthquake and tsunami effects on sandy beach ecosystems. Our study incorporated anthropogenic coastal development as a key design factor. Ecological responses of beach ecosystems were strongly affected by the magnitude of land-level change. Subsidence along the northern rupture segment combined with tsunami-associated disturbance and drowned beaches. In contrast, along the co-seismically uplifted southern rupture, beaches widened and flattened increasing habitat availability. Post-event changes in abundance and distribution of mobile intertidal invertebrates were not uniform, varying with land-level change, tsunami height and coastal development. On beaches where subsidence occurred, intertidal zones and their associated species disappeared. On some beaches, uplift of rocky subtidal substrate eliminated low intertidal sand beach habitat for ecologically important species. On others, unexpected interactions of uplift with man-made coastal armouring included restoration of upper and mid-intertidal habitat seaward of armouring followed by rapid colonization of mobile crustaceans typical of these zones formerly excluded by constraints imposed by the armouring structures. Responses of coastal ecosystems to major earthquakes appear to vary strongly with land-level change, the mobility of the biota and shore type. Our results show that interactions of extreme events with human-altered shorelines can produce surprising ecological outcomes, and suggest these complex responses to landscape alteration can leave lasting footprints in coastal ecosystems. Y1 - 2012 U6 - https://doi.org/10.1371/journal.pone.0035348 SN - 1932-6203 VL - 7 IS - 5 PB - PLoS CY - San Fransisco ER - TY - JOUR A1 - Melnick, Daniel A1 - Cisternas, Marco A1 - Moreno, Marcos A1 - Norambuena, Ricardo T1 - Estimating coseismic coastal uplift with an intertidal mussel calibration for the 2010 Maule Chile earthquake (M-w=8.8) JF - Quaternary science reviews : the international multidisciplinary research and review journal N2 - Coseismic coastal uplift has been quantified using sessile intertidal organisms after several great earthquakes following FitzRoy's pioneer measurements in 1835. A dense survey of such markers may complement space geodetic data to obtain an accurate distribution of fault slip and earthquake segmentation. However, uplift estimates based on diverse intertidal organisms tend to differ, because of few methodological and comparative studies. Here, we calibrate and estimate coastal uplift in the southern segment of the 2010 Maule, Chile earthquake (M-w = 8.8) using > 1100 post-earthquake elevation measurements of the sessile mussel Perumytilus purpuratus. This mussel is the predominant competitor for rocky shores all along the Pacific coast of South America, where it forms fringes or belts distinctively in the middle intertidal zone. These belts are centered at mean sea level and their width should equal one third of the tidal range. We measured belt widths close to this value at 40% of the sites, but overall widths are highly variable due to the unevenness in belt tops; belt bases, in turn, are rather regular. Belt top unevenness apparently results from locally-enhanced wave splash, whereas belt base evenness is controlled by predation. According to our measurements made beyond the earthquake rupture, the belt base is at the bottom of the middle intertidal zone, and thus we propose to estimate coastal uplift using the belt base mean elevation plus one sixth of the tidal range to reach mean sea level. Within errors our estimates agree with GPS displacements but differ from other methods. Comparisons of joint inversions for megathrust slip suggest combining space geodetic data with estimates from intertidal organisms may locally increase the detail of slip distributions. KW - Coastal uplift KW - Maule earthquake KW - Chile KW - Intertidal organisms KW - Perumytilus mussels KW - Slip distribution Y1 - 2012 U6 - https://doi.org/10.1016/j.quascirev.2012.03.012 SN - 0277-3791 VL - 42 IS - 5 SP - 29 EP - 42 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Rodil, Iván F. A1 - Jaramillo, Eduardo A1 - Hubbard, David M. A1 - Dugan, Jenifer E. A1 - Melnick, Daniel A1 - Velasquez, Carlos T1 - Responses of Dune Plant Communities to Continental Uplift from a Major Earthquake: Sudden Releases from Coastal Squeeze JF - PLoS one N2 - Vegetated dunes are recognized as important natural barriers that shelter inland ecosystems and coastlines suffering daily erosive impacts of the sea and extreme events, such as tsunamis. However, societal responses to erosion and shoreline retreat often result in man-made coastal defence structures that cover part of the intertidal and upper shore zones causing coastal squeeze and habitat loss, especially for upper shore biota, such as dune plants. Coseismic uplift of up to 2.0 m on the Peninsula de Arauco (South central Chile, ca. 37.5 degrees S) caused by the 2010 Maule earthquake drastically modified the coastal landscape, including major increases in the width of uplifted beaches and the immediate conversion of mid to low sandy intertidal habitat to supralittoral sandy habitat above the reach of average tides and waves. To investigate the early stage responses in species richness, cover and across-shore distribution of the hitherto absent dune plants, we surveyed two formerly intertidal armoured sites and a nearby intertidal unarmoured site on a sandy beach located on the uplifted coast of Llico (Peninsula de Arauco) over two years. Almost 2 years after the 2010 earthquake, dune plants began to recruit, then rapidly grew and produced dune hummocks in the new upper beach habitats created by uplift at the three sites. Initial vegetation responses were very similar among sites. However, over the course of the study, the emerging vegetated dunes of the armoured sites suffered a slowdown in the development of the spatial distribution process, and remained impoverished in species richness and cover compared to the unarmoured site. Our results suggest that when released from the effects of coastal squeeze, vegetated dunes can recover without restoration actions. However, subsequent human activities and management of newly created beach and dune habitats can significantly alter the trajectory of vegetated dune development. Management that integrates the effects of natural and human induced disturbances, and promotes the development of dune vegetation as natural barriers can provide societal and conservation benefits in coastal ecosystems. Y1 - 2015 U6 - https://doi.org/10.1371/journal.pone.0124334 SN - 1932-6203 VL - 10 IS - 5 PB - PLoS CY - San Fransisco ER - TY - JOUR A1 - Melnick, Daniel A1 - Moreno, Marcos A1 - Cisternas, Marco A1 - Tassara, Andres T1 - Darwin seismic gap closed by the 2010 Maule earthquake JF - Andean geology N2 - The Maule earthquake (Mw 8.8) that affected south-central Chile on February 27, 2010 was preceded by the 1835 event documented by FitzRoy and Darwin. The relation between both events has been controversial. Fault slip in 2010 estimated by Lorito et al. (2011) is less than expected from 175 years of strain accumulation, leading them to conclude only limited overlap between the 2010 and 1835 events, and that a Mw 7.5-8 event could still strike the Concepcion region. However, Lorito et al.'s model was based on displacements obtained from only 6 GPS stations and underpredicts observations from recent studies. Here we show that an alternative model based on 169 GPS displacements reproduces the data better, suggesting Lorito et al.'s main conclusion is not correct. Based on a slip deficit map, we suggest the seismic gap opened in 1835 was most likely closed in 2010. KW - Maule earthquake KW - Coseismic slip distribution KW - Slip deficit KW - Seismic gap Y1 - 2012 U6 - https://doi.org/10.5027/andgeoV39n3-a11 SN - 0718-7092 VL - 39 IS - 3 SP - 558 EP - 563 PB - Servicio Nacional de Geologìa y Minerìa CY - Santiago ER - TY - JOUR A1 - Pedoja, Kevin A1 - Husson, Laurent A1 - Johnson, Markes E. A1 - Melnick, Daniel A1 - Witt, Cesar A1 - Pochat, Stephane A1 - Nexer, Maelle A1 - Delcaillau, Bernard A1 - Pinegina, Tatiana A1 - Poprawski, Yohann A1 - Authemayou, Christine A1 - Elliot, Mary A1 - Regard, Vincent A1 - Garestier, Franck T1 - Coastal staircase sequences reflecting sea-level oscillations and tectonic uplift during the Quaternary and Neogene JF - Earth science reviews : the international geological journal bridging the gap between research articles and textbooks N2 - Many coasts feature sequences of Quaternary and Neogene shorelines that are shaped by a combination of sea-level oscillations and tectonics. We compiled a global synthesis of sea-level changes for the following highstands: MIS 1, MIS 3, MIS 5e and MIS 11. Also, we date the apparent onset of sequences of paleoshorelines either from published data or tentatively extrapolating an age for the uppermost, purported oldest shoreline in each sequence. Including the most documented MIS 5e benchmark, we identify 926 sequences out of which 185 also feature Holocene shorelines. Six areas are identified where elevations of the MIS 3 shorelines are known, and 31 feature elevation data for MIS 11 shorelines. Genetic relationships to regional geodynamics are further explored based on the elevations of the MIS 5e benchmark. Mean apparent uplift rates range from 0.01 0.01 mm/yr (hotspots) to 1.47 0.08 mm/yr (continental collision). Passive margins appear as ubiquitously uplifting, while tectonic segmentation is more important on active margins. From the literature and our extrapolations, we infer ages for the onset of formation for -180 coastal sequences. Sea level fingerprinting on coastal sequences started at least during mid Miocene and locally as early as Eocene. Whether due to the changes in the bulk volume of seawater or to the temporal variations in the shape of ocean basins, estimates of eustasy fail to explain the magnitude of the apparent sea level drop. Thus, vertical ground motion is invoked, and we interpret the longlasting development of those paleoshore sequences as the imprint of glacial cycles on globally uplifted margins in response to continental compression. The geomorphological expression of the sequences matches the amplitude and frequency of glacial cyclicity. From middle Pleistocene to present-day, moderately fast (100,000 yrs) oscillating sea levels favor the development of well identified strandlines that are distinct from one another. Pliocene and Lower Pleistocene strandlines associated with faster cyclicity (40,000 yrs) are more compact and easily merge into rasas, whereas older Cenozoic low-frequency eustatic changes generally led to widespread flat-lying coastal plains. KW - Cenozoic KW - Coastal sequence of shorelines KW - Strandlines KW - Rasa KW - Geodynamic Y1 - 2014 U6 - https://doi.org/10.1016/j.earscirev.2014.01.007 SN - 0012-8252 SN - 1872-6828 VL - 132 SP - 13 EP - 38 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Vargas, Gabriel A1 - Farias, Marcelo A1 - Carretier, Sebastien A1 - Tassara, Andres A1 - Baize, Stephane A1 - Melnick, Daniel T1 - Coastal uplift and tsunami effects associated to the 2010 M(w)8.8 Maule earthquake in Central Chile JF - Andean geology N2 - On February 27, 2010 at 03:34:08 AM an M(w)8.8 earthquake, with epicenter located off Cobquecura (73.24 degrees W; 36.29 degrees S), severely hit Central Chile. The tsunami waves that followed this event affected the coastal regions between the cities of Valparaiso and Valdivia, with minor effects as far as Coquimbo. The earthquake occurred along the subduction of the Nazca oceanic plate beneath the South American plate. Coseismic coastal uplift was estimated through observations of bleached lithothamnioids crustose coralline algae, which were exposed after the mainshock between 34.13 degrees S and 38.34 degrees S, suggesting the latitudinal distribution of the earthquake rupture. The measured coastal uplift values varied between 240 +/- 20 cm at sites closer to the trench along the western coast of the Arauco peninsula and 15 +/- 10 cm at sites located farther east. A maximum value of 260 +/- 50 cm was observed at the western coast of Santa Maria Island, which is similar to the reported uplift associated with the 1835 earthquake at Concepcion. Land subsidence values on the order of 0.5 m to 1 m evidenced a change in polarity and position of the coseismic hinge at 110-120 km from the trench. In four sites along the coast we observed a close match between coastal uplift values deduced from bleached lithothamnioids algae and GPS measurements. According to field observations tsunami heights reached ea. 14 m in the coastal area of the Maule Region immediately north of the epicenter, and diminished progressively northwards to 4-2 m near Valparaiso. Along the coast of Cobquecura, tsunami height values were inferior to 2-4 m. More variable tsunami heights of 6-8 m were measured at Dichato-Talcahuano and Tirua-Puerto Saavedra, in the Biobio and Arauco regions, respectively, to the south of the epicenter. According to eyewitnesses, the tsunami reached the coast between 12 to 20 and 30 to 45 minutes in areas located closer and faraway from the earthquake rupture zone, respectively. Destructive tsunami waves arrived also between 2.5 and 4.5 hours after the mainshock, especially along the coast of the Biobio and Arauco regions. The tsunami effects were highly variable along the coast, as a result of geomorphological and bathymetric local conditions, besides potential complexities induced by the main shock. KW - M(w)8.8 Maule earthquake KW - Central Chile KW - Coseismic coastal uplift KW - Tsunami effect Y1 - 2011 U6 - https://doi.org/10.5027/andgeoV38n1-a12 SN - 0718-7106 VL - 38 IS - 1 SP - 219 EP - 238 PB - Servicio Nacional de Geologìa y Minerìa CY - Santiago ER - TY - GEN A1 - Rodil, Iván F. A1 - Jaramillo, Eduardo A1 - Hubbard, David M. A1 - Dugan, Jenifer E. A1 - Melnick, Daniel A1 - Velasquez, Carlos T1 - Responses of dune plant communities to continental uplift from a major earthquake BT - sudden releases from coastal squeeze T2 - Postprints der Universität Potsdam : Mathematisch Naturwissenschaftliche Reihe N2 - Vegetated dunes are recognized as important natural barriers that shelter inland ecosystems and coastlines suffering daily erosive impacts of the sea and extreme events, such as tsunamis. However, societal responses to erosion and shoreline retreat often result in man-made coastal defence structures that cover part of the intertidal and upper shore zones causing coastal squeeze and habitat loss, especially for upper shore biota, such as dune plants. Coseismic uplift of up to 2.0 m on the Peninsula de Arauco (South central Chile, ca. 37.5 degrees S) caused by the 2010 Maule earthquake drastically modified the coastal landscape, including major increases in the width of uplifted beaches and the immediate conversion of mid to low sandy intertidal habitat to supralittoral sandy habitat above the reach of average tides and waves. To investigate the early stage responses in species richness, cover and across-shore distribution of the hitherto absent dune plants, we surveyed two formerly intertidal armoured sites and a nearby intertidal unarmoured site on a sandy beach located on the uplifted coast of Llico (Peninsula de Arauco) over two years. Almost 2 years after the 2010 earthquake, dune plants began to recruit, then rapidly grew and produced dune hummocks in the new upper beach habitats created by uplift at the three sites. Initial vegetation responses were very similar among sites. However, over the course of the study, the emerging vegetated dunes of the armoured sites suffered a slowdown in the development of the spatial distribution process, and remained impoverished in species richness and cover compared to the unarmoured site. Our results suggest that when released from the effects of coastal squeeze, vegetated dunes can recover without restoration actions. However, subsequent human activities and management of newly created beach and dune habitats can significantly alter the trajectory of vegetated dune development. Management that integrates the effects of natural and human induced disturbances, and promotes the development of dune vegetation as natural barriers can provide societal and conservation benefits in coastal ecosystems. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 516 KW - Chile earthquake KW - sandy-beach KW - New-Zealand KW - salt spray KW - vegetation KW - conservation KW - disturbance KW - protection KW - habitats KW - zonation Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-409629 SN - 1866-8372 IS - 516 ER - TY - JOUR A1 - Melnick, Daniel T1 - Rise of the central Andean coast by earthquakes straddling the Moho JF - Nature geoscience N2 - Surface movements during the largest subduction zone earthquakes commonly drown coastlines. Yet, on geological timescales, coastlines above subduction zones uplift. Here I use a morphometric analysis combined with a numerical model of landscape evolution to estimate uplift rates along the central Andean rasa-a low-relief coastal surface bounded by a steep cliff formed by wave erosion. I find that the rasa has experienced steady uplift of 0.13 +/- 0.04 mm per year along a stretch of more than 2,000 km in length, during the Quaternary. These long-term uplift rates do not correlate with Global Positioning System (GPS) measurements of interseismic movements over the decadal scale, which implies that permanent uplift is not predominantly accumulated during the interseismic period. Instead, the rate of rasa uplift correlates with slip during earthquakes straddling the crust-mantle transition, the Moho. Such deeper earthquakes with magnitude 7 to 8 that occurred between 1995 and 2012 resulted in decimetres of coastal uplift. Slip during these earthquakes is located below the locked portion of the plate interface, and therefore may translate into permanent deformation of the overlying plate, where it causes uplift of the coastline. Thus, lower parts of the plate boundary are stably segmented over hundreds to millions of years. I suggest the coastline marks the surface expression of the transition between the shallow, locked seismogenic domain and the deeper, conditionally stable domain where modest earthquakes build up topography. Y1 - 2016 U6 - https://doi.org/10.1038/NGEO2683 SN - 1752-0894 SN - 1752-0908 VL - 9 SP - 401 EP - + PB - Nature Publ. Group CY - New York ER - TY - JOUR A1 - Jara-Munoz, Julius A1 - Melnick, Daniel T1 - Unraveling sea-level variations and tectonic uplift in wave-built marine terraces, Santa Maria Island, Chile JF - Quaternary research : an interdisciplinary journal N2 - The architecture of coastal sequences in tectonically-active regions results mostly from a combination of sea-level and land-level changes. The objective of this study is to unravel these signals by combining sequence stratigraphy and sedimentology of near-shore sedimentary sequences in wave-built terraces. We focus on Santa Maria Island at the south-central Chile margin, which hosts excellent exposures of coastal sediments from Marine Isotope Stage 3. A novel method based on statistical analysis of grain-size distributions coupled with fades descriptions provided a detailed account of transgressive-regressive cycles. Radiocarbon ages from paleosols constrain the chronology between >53 and similar to 31 cal ka BP. Because the influence of glaciations can be neglected, we calculated relative sea-level curves by tying the onset of deposition on a bedrock abrasion platform to a global sea-level curve. The observed depositional cycles match those predicted for uplift rates between 1.2 and 1.8 m/ka. The studied sedimentary units represent depositional cycles that resulted in reoccupation events of an existing marine terrace. Our study demonstrates wave-built marine terrace deposits along clastic shorelines in temperate regions can be used to distinguish between tectonic uplift and climate-induced sea-level changes. KW - Marine terraces KW - Wave-built terraces KW - Terrace reoccupation KW - Tectonic uplift KW - Sea-level change KW - Coastal sedimentation Y1 - 2015 U6 - https://doi.org/10.1016/j.yqres.2014.10.002 SN - 0033-5894 SN - 1096-0287 VL - 83 IS - 1 SP - 216 EP - 228 PB - Elsevier CY - San Diego ER - TY - GEN A1 - Melnick, Daniel A1 - Li, Shaoyang A1 - Moreno, Marcos A1 - Cisternas, Marco A1 - Jara-Muñoz, Julius A1 - Wesson, Robert A1 - Nelson, Alan A1 - Báez, Juan Carlos A1 - Deng, Zhiguo T1 - Back to full interseismic plate locking decades after the giant 1960 Chile earthquake T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Great megathrust earthquakes arise from the sudden release of energy accumulated during centuries of interseismic plate convergence. The moment deficit (energy available for future earthquakes) is commonly inferred by integrating the rate of interseismic plate locking over the time since the previous great earthquake. But accurate integration requires knowledge of how interseismic plate locking changes decades after earthquakes, measurements not available for most great earthquakes. Here we reconstruct the post-earthquake history of plate locking at Guafo Island, above the seismogenic zone of the giant 1960 (M-w = 9.5) Chile earthquake, through forward modeling of land-level changes inferred from aerial imagery (since 1974) and measured by GPS (since 1994). We find that interseismic locking increased to similar to 70% in the decade following the 1960 earthquake and then gradually to 100% by 2005. Our findings illustrate the transient evolution of plate locking in Chile, and suggest a similarly complex evolution elsewhere, with implications for the time- and magnitude-dependent probability of future events. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 678 KW - south-central Chile KW - continuous GPS measurements KW - andean subduction zone KW - finite-element model KW - 2010 M8.8 maule KW - postseismic deformation KW - megathrust earthquake KW - afterslip KW - slip KW - resolution Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-425723 SN - 1866-8372 IS - 678 ER - TY - JOUR A1 - Racano, Simone A1 - Jara-Munoz, Julius A1 - Cosentino, Domenico A1 - Melnick, Daniel T1 - Variable quaternary uplift along the Southern Margin of the Central Anatolian Plateau inferred from modeling Marine Terrace sequences JF - Tectonics N2 - The southern margin of the Central Anatolian Plateau (CAP) records a strong uplift phase after the early Middle Pleistocene, which has been related to the slab break-off of the subducting Arabian plate beneath the Anatolian microplate. During the last 450 kyr the area underwent an uplift phase at a mean rate of similar to 3.2 m/kyr, as suggested by Middle Pleistocene marine sediments exposed at similar to 1,500 m above sea level. These values are significantly higher than the 1.0-1.5 m/kyr estimated since the Late Pleistocene, suggesting temporal variations in uplift rate. To estimate changes in uplift rate during the Pleistocene we studied the marine terraces along the CAP southern margin, mapping the remnants of the platforms and their associated deposits in the field, and used the TerraceM software to identify the position and elevation of associated shoreline angles. We used shoreline angles and the timing of Quaternary marine sedimentation as constrains for a Landscape Evolution Model that simulates wave erosion of an uplifting coast. We applied random optimization algorithms and minimization statistics to find the input parameters that better reproduce the morphology of CAP marine terraces. The best-fitting uplift rate history suggests a significative increase from 1.9 to 3.5 m/kyr between 500 and 200 kyr, followed by an abrupt decrease to 1.4 m/kyr until the present. Our results agree with slab break-off models, which suggest a strong uplift pulse during slab rupture followed by a smoother decrease. Y1 - 2020 U6 - https://doi.org/10.1029/2019TC005921 SN - 0278-7407 SN - 1944-9194 VL - 39 IS - 12 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Erbello Doelesso, Asfaw A1 - Melnick, Daniel A1 - Zeilinger, Gerold A1 - Bookhagen, Bodo A1 - Pingel, Heiko A1 - Strecker, Manfred T1 - Geomorphic expression of a tectonically active rift-transfer zone in southern Ethiopia JF - Geomorphology : an international journal on pure and applied geomorphology N2 - The Gofa Province and the Chew Bahir Basin of southern Ethiopia constitute tectonically active regions, where the Southern Main Ethiopian Rift converges with the Northern Kenya Rift through a wide zone of extensional deformation with several north to northeast-trending, left-stepping en-e & PRIME;chelon basins. This sector of the Southern Main Ethiopian Rift is characterized by a semi-arid climate and a largely uniform lithology, and thus provides ideal conditions for studying the different parameters that define the tectonic and geomorphic features of this complex kinematic transfer zone. In this study, the degree of tectonic activity, spatiotemporal variations in extension, and the nature of kinematic linkage between different fault systems of the transfer zone are constrained by detailed quantitative geomorphic analysis of river catchments and focused field work. We analyzed fluvial and landscape morphometric characteristics in combination with structural, seismicity, and climatic data to better evaluate the tectono-geomorphic history of this transfer zone. Our data reveal significant north-south variations in the degree of extension from the Sawula Basin in the north (mature) to the Chew Bahir Basin in the south (juvenile). First, normalized channel-steepness indices and the spatial arrangement of knickpoints in footwall-draining streams suggest a gradual, southward shift in extensional deformation and recent tectonic activity. Second, based on 1-k(m) radius local relief and mean-hillslope maximum values that are consistent with ksn anomalies, we confirm strain localization within zones of fault interaction. Third, morphometric indices such as hypsometry, basin asymmetry factor, and valley floor width to valley height ratio also indicate a north to south gradient in tectonic activity, highlighting the importance of such a wide transfer zone with diffuse extension linking different rift segments during the break-up of continental crust. KW - rift transfer zone KW - Ethiopia rift KW - renya Rift KW - morphometric indices KW - knickpoints Y1 - 2022 U6 - https://doi.org/10.1016/j.geomorph.2022.108162 SN - 0169-555X SN - 1872-695X VL - 403 PB - Elsevier Science CY - Amsterdam [u.a.] ER - TY - JOUR A1 - Bookhagen, Bodo A1 - Echtler, Helmut Peter A1 - Melnick, Daniel A1 - Strecker, Manfred A1 - Spencer, Joel Q. G. T1 - Using uplifted Holocene beach berms for paleoseismic analysis on the Santa Maria Island, south-central Chile N2 - Major earthquakes ( M > 8) have repeatedly ruptured the Nazca-South America plate interface of south-central Chile involving meter scale land-level changes. Earthquake recurrence intervals, however, extending beyond limited historical records are virtually unknown, but would provide crucial data on the tectonic behavior of forearcs. We analyzed the spatiotemporal pattern of Holocene earthquakes on Santa Maria Island (SMI; 37 degrees S), located 20 km off the Chilean coast and approximately 70 km east of the trench. SMI hosts a minimum of 21 uplifted beach berms, of which a subset were dated to calculate a mean uplift rate of 2.3 +/- 0.2 m/ky and a tilting rate of 0.022 +/- 0.002 degrees/ky. The inferred recurrence interval of strandline-forming earthquakes is similar to 180 years. Combining coseismic uplift and aseismic subsidence during an earthquake cycle, the net gain in strandline elevation in this environment is similar to 0.4 m per event Y1 - 2006 UR - http://www.agu.org/journals/gl/ U6 - https://doi.org/10.1029/2006gl026734 SN - 0094-8276 ER - TY - THES A1 - Melnick, Daniel T1 - Neogene seismotectonics of the south-central Chile margin : subduction-related processes over various temporal and spatial scales T1 - Neogene Seismotektonik des süd-zentralen chilenischen aktiven Plattenrandes : Subduktionsprozesse in unterschiedlichen Zeit- und Raumskalen N2 - The Andean orogen is the most outstanding example of mountain building caused by the subduction of oceanic below continental lithosphere. The Andes formed by the subduction of the Nazca and Antarctic oceanic plates under the South American continent over at least ~200 million years. Tectonic and climatic conditions vary markedly along this north-south–oriented plate boundary, which thus represents an ideal natural laboratory to study tectonic and climatic segmentation processes and their possible feedbacks. Most of the seismic energy on Earth is released by earthquakes in subduction zones, like the giant 1960, Mw 9.5 event in south-central Chile. However, the segmentation mechanisms of surface deformation during and between these giant events have remained poorly understood. The Andean margin is a key area to study seismotectonic processes because of its along-strike variability under similar plate kinematic boundary conditions. Active deformation has been widely studied in the central part of the Andes, but the south-central sector of the orogen has gathered less research efforts. This study focuses on tectonics at the Neogene and late Quaternary time scales in the Main Cordillera and coastal forearc of the south-central Andes. For both domains I document the existence of previously unrecognized active faults and present estimates of deformation rates and fault kinematics. Furthermore these data are correlated to address fundamental mountain building processes like strain partitioning and large-scale segmentation. In the Main Cordillera domain and at the Neogene timescale, I integrate structural and stratigraphic field observations with published isotopic ages to propose four main phases of coupled styles of tectonics and distribution of volcanism and magmatism. These phases can be related to the geometry and kinematics of plate convergence. At the late Pleistocene timescale, I integrate field observations with lake seismic and bathymetric profiles from the Lago Laja region, located near the Andean drainage divide. These data reveal Holocene extensional faults, which define the Lago Laja fault system. This fault system has no significant strike-slip component, contrasting with the Liquiñe-Ofqui dextral intra-arc system to the south, where Holocene strike-slip markers are ubiquitous. This contrast in structural style along the arc is coincident with a marked change in along-strike fault geometries in the forearc, across the Arauco Peninsula. Thereon I propose that a net gradient in the degree of partitioning of oblique subduction occurs across the Arauco transition zone. To the north, the margin parallel component of oblique convergence is distributed in a wide zone of diffuse deformation, while to the south it is partitioned along an intra-arc, margin-parallel strike-slip fault zone. In the coastal forearc domain and at the Neogene timescale, I integrate structural and stratigraphic data from field observations, industry reflection-seismic profiles and boreholes to emphasize the influence of climate-driven filling of the trench on the mechanics and kinematics of the margin. I show that forearc basins in the 34-45°S segment record Eocene to early Pliocene extension and subsidence followed by ongoing uplift and contraction since the late Pliocene. I interpret the first stage as caused by tectonic erosion due to high plate convergence rates and reduced trench fill. The subsequent stage, in turn, is related to accretion caused by low convergence rates and the rapid increase in trench fill after the onset of Patagonian glaciations and climate-driven exhumation at ~6-5 Ma. On the late Quaternary timescale, I integrate off-shore seismic profiles with the distribution of deformed marine terraces from Isla Santa María, dated by the radiocarbon method, to show that inverted reverse faulting controls the coastal geomorphology and segmentation of surface deformation. There, a cluster of microearthquakes illuminates one of these reverse faults, which presumingly reaches the plate interface. Furthermore, I use accounts of coseismic uplift during the 1835 M>8 earthquake made by Charles Darwin, to propose that this active reverse fault has been mechanically coupled to the megathrust. This has important implications on the assessment of seismic hazards in this, and other similar regions. These results underscore the need to study plate-boundary deformation processes at various temporal and spatial scales and to integrate geomorphologic, structural, stratigraphic, and geophysical data sets in order to understand the present distribution and causes of tectonic segmentation. N2 - Die Anden sind eine einzigartige Gebirgskette entstanden aus der Subduktion von ozeanischer unter kontinentale Lithosphäre. Seit mehr als 200 Millionen Jahren bewirkt die Subduktion der ozeanischen Nazca- und Antarktisplatte unter den Südamerikanischen Kontinent eine stete Entwicklung des aktiven Plattenrandsystems. Entlang der Plattengrenze ändern sich die tektonischen und klimatischen Bedingungen in markanter Weise und machen dieses Orogen zu einem idealen natürlichen Laboratorium für das Studium tektonischer und klimatischer Prozesse und deren rückgekoppelte Wechselwirkungen. Der grösste Teil der seismischen Energie auf der Erde wird durch Erdbeben an Subduktionszonen freigesetzt, wie das spektakulärste Beispiel des Valdivia-Bebebens von 1960 im süd-zentral chilenischen Küstenbereich – mit Mw 9,5 das stärkste je gemessene seismische Ereignis, unterstreicht. Die Verteilungsmechanismen der Oberflächendeformation während und zwischen solchen gewaltigen Vorgängen blieben jedoch weitgehend unverstanden. Wegen seiner im Streichen veränderlichen Eigenschaften bei ähnlich bleibenden plattenkinematischen Randbedingungen nimmt die Subduktionszone des Anden-Orogens eine Schlüsselstellung für das Studium seismotektonischer Segmentationsprozesse ein. Aktive Deformationsprozesse sind im zentralen Teil der Anden in grösserem Umfang untersucht worden, während der mittlere bis südliche Abschnitt des Orogens bisher weniger Bearbeitung fand. Die vorliegende Arbeit ist auf die seismotektonischen Prozesse des Neogen und Spätquartärs in der Hauptkordillere und dem Küstenbereich der südlichen Zentralanden konzentriert. In beiden Strukturzonen kann die Existenz bisher nicht bekannter aktiver Störungen belegt werden und es werden Abschätzungen der Deformationsraten sowie der Kinematik präsentiert. Diese Daten bilden desweiteren die Basis, um Aussagen zu grundlegenden gebirgsbildenden Prozessen, der Verformungsverteilung und der gross-skaligen Segmentation zu treffen. Für das Neogen im untersuchten Abschnitt der Hauptkordillere sind strukturelle und stratigraphische Geländebeobachtungen durch publizierte Isotopendaten ergänzt worden, so dass vier Hauptphasen mit jeweils spezifischem tektonischen Stil und Verteilungsmustern von Vulkanismus und Magmatismus unterschieden werden können. Auf der spätpleistozänen Zeitskala sind die Geländebeobachtungen mit seismischen und bathymetrischen Seeprofilen aus der Lago-Laja-Region kombiniert worden, die sich nahe der Wasserscheide der Anden befinden. Diese Daten belegen extensionale holozäne Störungen, die das Lago-Laja-Störungssystem bestimmen. Im Gegensatz zum dextralen Liquiñe-Ofqui-System im Süden, wo holozäne, dextrale Blattverschiebungen allgegenwärtig sind, besitzt dieses Störungssystem keine signifikante Blattverschiebungskomponente. Dieser Kontrast entlang der Kordilliere fällt mit einer markanten Änderung der Störungsmuster im Forearc zusammen. Im Norden verteilt sich die randparallele Komponente der schrägen Subduktion auf eine breite Zone diffuser Verformung, während sie im Süden entlang einer Intra-arc- und randparallelen Blattverschiebungszone partitioniert auftritt. Im Küstenbereich werden Struktur- und stratigraphische Daten aus Geländebeobachtungen mit reflektionsseismischen Profilen und Bohrlochmessdaten verbunden, um Information zum Einfluss einer klimatisch-gesteuerten Auffüllung des Grabens auf die Mechanismen und die Kinematik des Randes während des Neogen zu erhalten. Es zeigt sich, dass Forearc-Becken im Segment bei 34–45° S eozäne bis frühpliozäne Dehnung und Subsidenz aufzeigen, denen spätpliozäne und noch aktive Hebung und Verkürzung folgten. Das erste Stadium kann mit tektonischer Erosion infolge hoher Plattenkonvergenzraten und geringerer Grabenfüllung erklärt werden. Das nachfolgende Stadium hingegen ist mit Akkretionsprozessen zu erklären, die durch geringe Konvergenzraten und gesteigerte Grabenauffüllung nach dem Einsetzen der Patagonischen Vereisung und klimagesteuerter Exhumierung vor etwa 6–5 Ma verursacht wurden. Auf der spätpleistozänen Zeitebene werden seismische Profile mit der Oberflächenentwicklung aus deformierten, 14C-datierten, marinen Terrassen der Isla Santa María integriert und gezeigt dass die Küstenmorphologie und die Segmentation der Oberflächendeformation von Aufschiebungen kontrolliert werden. In diesem Gebiet zeichnet ein Cluster von Mikrobeben eine dieser Störungen, die vermutlich die Plattengrenzfläche erreicht, deutlich nach. Desweiteren zeigen Berechnungen der koseismischen Hebung während des Erdbebens von 1835 mit M>8 nach Aufzeichnungen von Charles Darwin, dass diese aktive Verwerfung mechanisch an die Subduktionszone gekoppelt war und durch das Ereignis von 1835 aktiviert wurde. Diese Erkenntnisse haben grosse Bedeutung für die Abschätzung der seismischen Gefährdung in der Region. Die gewonnenen Ergebnisse dieser Arbeit unterstreichen den Bedarf an integrierten Untersuchungen der Deformationsprozesse an aktiven Plattenrändern in verschiedenen Zeit- und Raumskalen, ebenso wie die Notwendigkeit, diese mit geomorphologischen, strukturellen und geophysikalischen Datensätzen zu verknüpfen, um einen Beitrag zum Verständnis der gegenwärtigen Verteilung und Ursachen der tektonischen Segmentation sowie der Gefährdungsabschätzung zu leisten. KW - Seismotektonik KW - Chile KW - neogene KW - seismotectonics KW - Chile Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-12091 ER - TY - JOUR A1 - Jara-Munoz, Julius A1 - Melnick, Daniel A1 - Pedoja, Kevin A1 - Strecker, Manfred T1 - TerraceM-2: A MatlabR (R) Interface for Mapping and Modeling Marine and Lacustrine Terraces JF - Frontiers in Earth Science N2 - The morphology of marine and lacustrine terraces has been largely used to measure past sea- and lake-level positions and estimate vertical deformation in a wealth of studies focused on climate and tectonic processes. To obtain accurate morphometric assessments of terrace morphology we present TerraceM-2, an improved version of our MatlabR (R) graphic-user interface that provides new methodologies for morphometric analyses as well as landscape evolution and fault-dislocation modeling. The new version includes novel routines to map the elevation and spatial distribution of terraces, to model their formation and evolution, and to estimate fault-slip rates from terrace deformation patterns. TerraceM-2 has significantly improves its processing speed and mapping capabilities, and includes separate functions for developing customized workflows beyond the graphic-user interface. We illustrate these new mapping and modeling capabilities with three examples: mapping lacustrine shorelines in the Dead Sea to estimate deformation across the Dead Sea Fault, landscape evolution modeling to estimate a history of uplift rates in southern Peru, and dislocation modeling of deformed marine terraces in California. These examples also illustrate the need to use topographic data of different resolutions. The new modeling and mapping routines of TerraceM-2 highlight the advantages of an integrated joint mapping and modeling approach to improve the efficiency and precision of coastal terrace metrics in both marine and lacustrine environments. KW - TerraceM KW - marine terraces KW - tectonic geomorphology KW - geomorphic markers KW - LiDAR KW - coastal geomorphology KW - neotectonics KW - morphometry Y1 - 2019 U6 - https://doi.org/10.3389/feart.2019.00255 SN - 2296-6463 VL - 7 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Garcin, Yannick A1 - Junginger, Annett A1 - Melnick, Daniel A1 - Olago, Daniel O. A1 - Strecker, Manfred A1 - Trauth, Martin H. T1 - Late Pleistocene-Holocene rise and collapse of the Lake Suguta, northern Kenya Rift Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/02773791 U6 - https://doi.org/10.1016/j.quascirev.2008.12.006 ER - TY - JOUR A1 - Yildirim, Cengiz A1 - Schildgen, Taylor F. A1 - Echtler, Helmut Peter A1 - Melnick, Daniel A1 - Strecker, Manfred T1 - Late Neogene and active orogenic uplift in the Central Pontides associated with the North Anatolian Fault implications for the northern margin of the Central Anatolian Plateau, Turkey JF - Tectonics N2 - Surface uplift at the northern margin of the Central Anatolian Plateau (CAP) is integrally tied to the evolution of the Central Pontides (CP), between the North Anatolian Fault (NAF) and the Black Sea. Our regional morphometric and plate kinematic analyses reveal topographic anomalies, steep channel gradients, and local high relief areas as indicators of ongoing differential surface uplift, which is higher in the western CP compared to the eastern CP and fault-normal components of geodetic slip vectors and the character of tectonic activity of the NAF suggest that stress is accumulated in its broad restraining bend. Seismic reflection and structural field data show evidence for a deep structural detachment horizon responsible for the formation of an actively northward growing orogenic wedge with a positive flower-structure geometry across the CP and the NAF. Taken together, the tectonic, plate kinematic, and geomorphic observations imply that the NAF is the main driving mechanism for wedge tectonics and uplift in the CP. In addition, the NAF Zone defines the boundary between the extensional CAP and the contractional CP. The syntectonic deposits within inverted intermontane basins and deeply incised gorges suggest that the formation of relief, changes in sedimentary dynamics, and > 1 km fluvial incision resulted from accelerated uplift starting in the early Pliocene. The Central Pontides thus provide an example of an accretionary wedge with surface-breaking faults that play a critical role in mountain building processes, sedimentary basin development, and ensuing lateral growth of a continental plateau since the end of the Miocene. Y1 - 2011 U6 - https://doi.org/10.1029/2010TC002756 SN - 0278-7407 VL - 30 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Melnick, Daniel A1 - Hillemann, Christian A1 - Jara Muñoz, Julius A1 - Garrett, Ed A1 - Cortes-Aranda, Joaquin A1 - Molina, Diego A1 - Tassara, Andrés A1 - Strecker, Manfred T1 - Hidden Holocene Slip Along the Coastal El Yolki Fault in Central Chile and Its Possible Link With Megathrust Earthquakes JF - Journal of geophysical research : Solid earth N2 - Megathrust earthquakes are commonly accompanied by increased upper-plate seismicity and occasionally triggered fault slip. In Chile, crustal faults slipped during and after the 2010 Maule (M8.8) earthquake. We studied the El Yolki fault (EYOF), a transtensional structure midways the Maule rupture not triggered in 2010. We mapped a Holocene coastal plain using light detection and ranging, which did not reveal surface ruptures. However, the inner-edge and shoreline angles along the coastal plain as well as 4.3- to 4.0-ka intertidal sediments are back-tilted on the EYOF footwall block, documenting 10 m of vertical displacement. These deformed markers imply similar to 2-mm/year throw rate, and dislocation models a slip rate of 5.6 mm/year for the EYOF. In a 5-m-deep trench, the Holocene intertidal sediments onlap to five erosive steps, interpreted as staircase wave-cut landforms formed by discrete events of relative sea level drop. We tentatively associated these steps with coseismic uplift during EYOF earthquakes between 4.3 and 4.0 ka. The Maule earthquake rupture may be subdivided into three subsegments based on coseismic slip and gravity anomalies. Coulomb stress transfer models predict neutral stress changes at the EYOF during the Maule earthquake but positive changes for a synthetic slip distribution at the central subsegment. If EYOF earthquakes were triggered by megathrust events, their slip distribution was probably focused in the central subsegment. Our study highlights the millennial variability of crustal faulting and the megathrust earthquake cycle in Chile, with global implications for assessing the hazards posed by hidden but potentially seismogenic coastal faults along subduction zones. KW - Central Chile KW - megathrust earthquake KW - crustal fault KW - seismotectonic segmentation KW - Middle Holocene KW - sea level change Y1 - 2019 U6 - https://doi.org/10.1029/2018JB017188 SN - 2169-9313 SN - 2169-9356 VL - 124 IS - 7 SP - 7280 EP - 7302 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Yildirim, Cengiz A1 - Melnick, Daniel A1 - Ballato, Paolo A1 - Schildgen, Taylor F. A1 - Echtler, Helmut Peter A1 - Erginal, A. Evren A1 - Kiyak, Nafiye Gunec A1 - Strecker, Manfred T1 - Differential uplift along the northern margin of the Central Anatolian Plateau - inferences from marine terraces JF - Quaternary science reviews : the international multidisciplinary research and review journal N2 - Emerged marine terraces and paleoshorelines along plate margins are prominent geomorphic markers that can be used to quantify the rates and patterns of crustal deformation. The northern margin of the Central Anatolian Plateau has been interpreted as an actively deforming orogenic wedge between the North Anatolian Fault and the Black Sea. Here we use uplifted marine terraces across principal faults on the Sinop Peninsula at the central northern side of the Pontide orogenic wedge to unravel patterns of Quaternary faulting and orogenic wedge behavior. We leveled the present-day elevations of paleoshorelines and dated marine terrace deposits using optically stimulated luminescence (OSL) to determine coastal uplift. The elevations of the paleoshorelines vary between 4 +/- 0.2 and 67 +/- 1.4 m above sea level and OSL ages suggest terrace formation episodes during interglacial periods at ca 125, 190, 400 and 570 ka, corresponding to marine isotopic stages (MIS) 5e, 7a, 11 and 15. Mean apparent vertical displacement rates (without eustatic correction) deduced from these terraces range between 0.02 and 0.18 mm/a, with intermittent faster rates of up to 0.26 mm/a. We obtained higher rates at the eastern and southern parts of the peninsula, toward the hinterland, indicating non-uniform uplift across the different morphotectonic segments of the peninsula. Our data are consistent with active on- and offshore faulting across the Sinop Peninsula. When integrated with regional tectonic observations, the faulting pattern reflects shortening distributed over a broad region of the northern margin of the Central Anatolian Plateau during the Quaternary. KW - Orogenic Plateaus KW - Central Anatolian Plateau KW - Plateau margins KW - Central Pontides KW - Orogenic wedges KW - Black Sea KW - Marine terraces KW - Uplift rate Y1 - 2013 U6 - https://doi.org/10.1016/j.quascirev.2013.09.011 SN - 0277-3791 VL - 81 IS - 4 SP - 12 EP - 28 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Yildirim, Cengiz A1 - Schildgen, Taylor F. A1 - Echtler, Helmut Peter A1 - Melnick, Daniel A1 - Bookhagen, Bodo A1 - Ciner, T. Attila A1 - Niedermann, Samuel A1 - Merchel, Silke A1 - Martschini, Martin A1 - Steier, Peter A1 - Strecker, Manfred T1 - Tectonic implications of fluvial incision and pediment deformation at the northern margin of the Central Anatolian Plateau based on multiple cosmogenic nuclides JF - Tectonics N2 - We document Quaternary fluvial incision driven by fault-controlled surface deformation in the inverted intermontane Gökirmak Basin in the Central Pontide mountains along the northern margin of the Central Anatolian Plateau. In-situ-produced Be-10, Ne-21, and Cl-36 concentrations from gravel-covered fluvial terraces and pediment surfaces along the trunk stream of the basin (the Gökirmak River) yield model exposure ages ranging from 71ka to 34645ka and average fluvial incision rates over the past similar to 350ka of 0.280.01mm a(-1). Similarities between river incision rates and coastal uplift rates at the Black Sea coast suggest that regional uplift is responsible for the river incision. Model exposure ages of deformed pediment surfaces along tributaries of the trunk stream range from 605ka to 110 +/- 10ka, demonstrating that the thrust faults responsible for pediment deformation were active after those times and were likely active earlier as well as explaining the topographic relief of the region. Together, our data demonstrate cumulative incision that is linked to active internal shortening and uplift of similar to 0.3mm a(-1) in the Central Pontide orogenic wedge, which may ultimately contribute to the lateral growth of the northern Anatolian Plateau. KW - Tectonic Geomorphology KW - Fluvial Incision KW - Surface Exposure Age KW - Uplift Rate Y1 - 2013 U6 - https://doi.org/10.1002/tect.20066 SN - 0278-7407 SN - 1944-9194 VL - 32 IS - 5 SP - 1107 EP - 1120 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Bernhardt, Anne A1 - Melnick, Daniel A1 - Jara-Munoz, Julius A1 - Argandona, Boris A1 - Gonzalez, Javiera A1 - Strecker, Manfred T1 - Controls on submarine canyon activity during sea-level highstands: The Biobio canyon system offshore Chile JF - Geosphere N2 - Newly acquired high-resolution bathymetric data (with 5 m and 2 m grid sizes) from the continental shelf off Concepcion (Chile), in combination with seismic reflection profiles, reveal a distinctly different evolution for the Biobio submarine canyon compared to that of one of its tributaries. Both canyons are incised into the shelf of the active margin. Whereas the inner shelf appears to be mantled with unconsolidated sediment, the outer shelf shows the influence of strong bottom currents that form drifts of loose sediment and transport -material into the Biobio submarine canyon and onto the continental slope. The main stem of the Biobio Canyon is connected to the mouth of the Biobio River and currently provides a conduit for terrestrial sediment from the continental shelf to the deep seafloor. In contrast, the head of its tributary closest to the coast is located similar to 24 km offshore of the present-day coastline at 120 m water depth, and it is subject to passive sedimentation. However, canyon activity within the study area is interpreted to be controlled not only by the direct input of fluvial sediments into the canyon head facilitated by the river-mouth to canyon-head connection, but also by input from southward-directed bottom currents and possibly longshore drift. In addition, about 24 km offshore of the present-day coastline, the main stem of the Biobio Canyon has steep canyon walls next to sites of active tectonic deformation that are prone to wall failure. Mass-failure events may also foster turbidity currents and contribute to canyon feeding. In contrast, the tributary has less steep canyon walls with limited evidence of canyon-wall failure and is located down-system of bottom currents from the Biobio Canyon. It consequently receives neither fluvial nor longshore sediments. Therefore, the canyon's connectivity to fluvial or longshore sediment delivery pathways is affected by the distance of the canyon head from the coastline and the orientation of the canyon axis relative to the direction of bottom currents. The ability of a submarine canyon to act as an active conduit for large quantities of terrestrial sediment toward the deep sea during sea-level highstands may be controlled by several different conditions simultaneously. These include bottom current direction, structural deformation of the seafloor affecting canyon location and orientation as well as canyon-wall failure, shelf gradient and associated distance from the canyon head to the coast, and fluvial networks. The complex interplay between these factors may vary even within an individual canyon system, resulting in distinct levels of canyon activity on a regional scale. Y1 - 2015 U6 - https://doi.org/10.1130/GES01063.1 SN - 1553-040X VL - 11 IS - 4 SP - 1226 EP - 1255 PB - American Institute of Physics CY - Boulder ER - TY - JOUR A1 - Bernhardt, Anne A1 - Melnick, Daniel A1 - Hebbeln, Dierk A1 - Lückge, Andreas A1 - Strecker, Manfred T1 - Turbidite paleoseismology along the active continental margin of Chile - Feasible or not? JF - Quaternary science reviews : the international multidisciplinary research and review journal N2 - Much progress has been made in estimating recurrence intervals of great and giant subduction earthquakes using terrestrial, lacustrine, and marine paleoseismic archives. Recent detailed records suggest these earthquakes may have variable recurrence periods and magnitudes forming supercycles. Understanding seismic supercycles requires long paleoseismic archives that record timing and magnitude of such events. Turbidite paleoseismic archives may potentially extend past earthquake records to the Pleistocene and can thus complement commonly shorter-term terrestrial archives. However, in order to unambiguously establish recurring seismicity as a trigger mechanism for turbidity currents, synchronous deposition of turbidites in widely spaced, isolated depocenters has to be ascertained. Furthermore, characteristics that predispose a seismically active continental margin to turbidite paleoseismology and the correct sample site selection have to be taken into account. Here we analyze 8 marine sediment cores along 950 km of the Chile margin to test for the feasibility of compiling detailed and continuous paleoseismic records based on turbidites. Our results suggest that the deposition of areally widespread, synchronous turbidites triggered by seismicity is largely controlled by sediment supply and, hence, the climatic and geomorphic conditions of the adjacent subaerial setting. The feasibility of compiling a turbidite paleoseismic record depends on the delicate balance between sufficient sediment supply providing material to fail frequently during seismic shaking and sufficiently low sedimentation rates to allow for coeval accumulation of planktonic foraminifera for high-resolution radiocarbon dating. We conclude that offshore northern central Chile (29-32.5 degrees S) Holocene turbidite paleoseismology is not feasible, because sediment supply from the semi-arid mainland is low and almost no Holocene turbidity-current deposits are found in the cores. In contrast, in the humid region between 36 and 38 degrees S frequent Holocene turbidite deposition may generally correspond to paleoseismic events. However, high terrigenous sedimentation rates prevent high-resolution radiocarbon dating. The climatic transition region between 32.5 and 36 degrees S appears to be best suited for turbidite paleoseismology. (C) 2015 Elsevier Ltd. All rights reserved. KW - Turbidite paleoseismology KW - Chile convergent margin KW - Earthquake KW - Seismoturbidites Y1 - 2015 U6 - https://doi.org/10.1016/j.quascirev.2015.04.001 SN - 0277-3791 VL - 120 SP - 71 EP - 92 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Jara-Munoz, Julius A1 - Melnick, Daniel A1 - Brill, Dominik A1 - Strecker, Manfred T1 - Segmentation of the 2010 Maule Chile earthquake rupture from a joint analysis of uplifted marine terraces and seismic-cycle deformation patterns JF - Quaternary science reviews : the international multidisciplinary research and review journal N2 - The segmentation of major fault systems in subduction zones controls earthquake magnitude and location, but the causes for the existence of segment boundaries and the relationships between long-term deformation and the extent of earthquake rupture, are poorly understood. We compare permanent and seismic-cycle deformation patterns along the rupture zone of the 2010 Maule earthquake (M8.8), which ruptured 500 km of the Chile subduction margin. We analyzed the morphology of MIS-5 marine terraces using LiDAR topography and established their chronology and coeval origin with twelve luminescence ages, stratigraphy and geomorphic correlation, obtaining a virtually continuous distribution of uplift rates along the entire rupture zone. The mean uplift rate for these terraces is 0.5 m/ka. This value is exceeded in three areas, which have experienced rapid emergence of up to 1.6 m/ka; they are located at the northern, central, and southern sectors of the rupture zone, referred to as Topocalma, Carranza and Arauco, respectively. The three sectors correlate with boundaries of eight great earthquakes dating back to 1730. The Topocalma and Arauco sectors, located at the boundaries of the 2010 rupture, consist of broad zones of crustal warping with wavelengths of 60 and 90 km, respectively. These two regions coincide with the axes of oroclinal bending of the entire Andean margin and correlate with changes in curvature of the plate interface. Rapid uplift at Carranza, in turn, is of shorter wavelength and associated with footwall flexure of three crustal-scale normal faults. The uplift rate at Carranza is inversely correlated with plate coupling as well as with coseismic slip, suggesting permanent deformation may accumulate interseismically. We propose that the zones of upwarping at Arauco and Topocalma reflect changes in frictional properties of the megathrust resulting in barriers to the propagation of great earthquakes. Slip during the 1960 (M9.5) and 2010 events overlapped with the similar to 90-km-long zone of rapid uplift at Arauco; similarly, slip in 2010 and 1906 extended across the similar to 60-km-long section of the megathrust at Topocalma, but this area was completely breached by the 1730 (M similar to 9) event, which propagated southward until Carranza. Both Arauco and Topocalma show evidence of sustained rapid uplift since at least the middle Pleistocene. These two sectors might thus constitute discrete seismotectonic boundaries restraining most, but not all great earthquake ruptures. Based on our observations, such barriers might be breached during multi-segment super-cycle events. (C) 2015 Elsevier Ltd. All rights reserved. KW - LiDAR KW - Subduction earthquakes KW - Marine terraces KW - Seismotectonic segmentation KW - Permanent uplift KW - Maule earthquake KW - Coastal uplift KW - TerraceM Y1 - 2015 U6 - https://doi.org/10.1016/j.quascirev.2015.01.005 SN - 0277-3791 VL - 113 SP - 171 EP - 192 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Jara-Muñoz, Julius A1 - Melnick, Daniel A1 - Li, Shaoyang A1 - Socquet, Anne A1 - Cortés-Aranda, Joaquín A1 - Brill, Dominik A1 - Strecker, Manfred T1 - The cryptic seismic potential of the Pichilemu blind fault in Chile revealed by off-fault geomorphology JF - Nature Communications N2 - The first step towards assessing hazards in seismically active regions involves mapping capable faults and estimating their recurrence times. While the mapping of active faults is commonly based on distinct geologic and geomorphic features evident at the surface, mapping blind seismogenic faults is complicated by the absence of on-fault diagnostic features. Here we investigated the Pichilemu Fault in coastal Chile, unknown until it generated a Mw 7.0 earthquake in 2010. The lack of evident surface faulting suggests activity along a partly-hidden blind fault. We used off-fault deformed marine terraces to estimate a fault-slip rate of 0.52 ± 0.04 m/ka, which, when integrated with satellite geodesy suggests a 2.12 ± 0.2 ka recurrence time for Mw~7.0 normal-faulting earthquakes. We propose that extension in the Pichilemu region is associated with stress changes during megathrust earthquakes and accommodated by sporadic slip during upper-plate earthquakes, which has implications for assessing the seismic potential of cryptic faults along convergent margins and elsewhere. Y1 - 2022 U6 - https://doi.org/10.1038/s41467-022-30754-1 SN - 2041-1723 VL - 13 PB - Springer Nature CY - London ER - TY - JOUR A1 - Freisleben, Roland A1 - Jara-Munoz, Julius A1 - Melnick, Daniel A1 - Miguel Martinez, Jose A1 - Strecker, Manfred T1 - Marine terraces of the last interglacial period along the Pacific coast of South America (1 degrees N-40 degrees S) JF - Earth system science data : ESSD N2 - Tectonically active coasts are dynamic environments characterized by the presence of multiple marine terraces formed by the combined effects of wave erosion, tectonic uplift, and sea-level oscillations at glacialcycle timescales. Well-preserved erosional terraces from the last interglacial sea-level highstand are ideal marker horizons for reconstructing past sea-level positions and calculating vertical displacement rates. We carried out an almost continuous mapping of the last interglacial marine terrace along similar to 5000 km of the western coast of South America between 1 degrees N and 40 degrees S. We used quantitatively replicable approaches constrained by published terrace-age estimates to ultimately compare elevations and patterns of uplifted terraces with tectonic and climatic parameters in order to evaluate the controlling mechanisms for the formation and preservation of marine terraces and crustal deformation. Uncertainties were estimated on the basis of measurement errors and the distance from referencing points. Overall, our results indicate a median elevation of 30.1 m, which would imply a median uplift rate of 0.22 m kyr(-1) averaged over the past similar to 125 kyr. The patterns of terrace elevation and uplift rate display high-amplitude (similar to 100-200 m) and long-wavelength (similar to 10(2) km) structures at the Manta Peninsula (Ecuador), the San Juan de Marcona area (central Peru), and the Arauco Peninsula (south-central Chile). Medium-wavelength structures occur at the Mejillones Peninsula and Topocalma in Chile, while short-wavelength (< 10 km) features are for instance located near Los Vilos, Valparaiso, and Carranza, Chile. We interpret the long-wavelength deformation to be controlled by deep-seated processes at the plate interface such as the subduction of major bathymetric anomalies like the Nazca and Carnegie ridges. In contrast, short-wavelength deformation may be primarily controlled by sources in the upper plate such as crustal faulting, which, however, may also be associated with the subduction of topographically less pronounced bathymetric anomalies. Latitudinal differences in climate additionally control the formation and preservation of marine terraces. Based on our synopsis we propose that increasing wave height and tidal range result in enhanced erosion and morphologically well-defined marine terraces in south-central Chile. Our study emphasizes the importance of using systematic measurements and uniform, quantitative methodologies to characterize and correctly interpret marine terraces at regional scales, especially if they are used to unravel the tectonic and climatic forcing mechanisms of their formation. This database is an integral part of the World Atlas of Last Interglacial Shorelines (WALIS), published online at https://doi.org/10.5281/zenodo.4309748 (Freisleben et al., 2020). Y1 - 2021 U6 - https://doi.org/10.5194/essd-13-2487-2021 SN - 1866-3508 SN - 1866-3516 VL - 13 IS - 6 SP - 2487 EP - 2513 PB - Copernics Publications CY - Katlenburg-Lindau ER - TY - JOUR A1 - Melnick, Daniel A1 - Bookhagen, Bodo A1 - Strecker, Manfred A1 - Echtler, Helmut Peter T1 - Segmentation of megathrust rupture zones from fore-arc deformation patterns over hundreds to millions of years, Arauco peninsula, Chile N2 - This work explores the control of fore-arc structure on segmentation of megathrust earthquake ruptures using coastal geomorphic markers. The Arauco-Nahuelbuta region at the south-central Chile margin constitutes an anomalous fore- arc sector in terms of topography, geology, and exhumation, located within the overlap between the Concepcion and Valdivia megathrust segments. This boundary, however, is only based on similar to 500 years of historical records. We integrate deformed marine terraces dated by cosmogenic nuclides, syntectonic sediments, published fission track data, seismic reflection profiles, and microseismicity to analyze this earthquake boundary over 10(2) -10(6) years. Rapid exhumation of Nahuelbuta's dome-like core started at 4 +/- 1.2 Ma, coeval with inversion of the adjacent Arauco basin resulting in emergence of the Arauco peninsula. Here, similarities between topography, spatiotemporal trends in fission track ages, Pliocene-Pleistocene growth strata, and folded marine terraces suggest that margin-parallel shortening has dominated since Pliocene time. This shortening likely results from translation of a fore-arc sliver or microplate, decoupled from South America by an intra-arc strike-slip fault. Microplate collision against a buttress leads to localized uplift at Arauco accrued by deep-seated reverse faults, as well as incipient oroclinal bending. The extent of the Valdivia segment, which ruptured last in 1960 with an M-w 9.5 event, equals the inferred microplate. We propose that mechanical homogeneity of the fore-arc microplate delimits the Valdivia segment and that a marked discontinuity in the continental basement at Arauco acts as an inhomogeneous barrier controlling nucleation and propagation of 1960-type ruptures. As microplate-related deformation occurs since the Pliocene, we propose that this earthquake boundary and the extent of the Valdivia segment are spatially stable seismotectonic features at million year scale. Y1 - 2009 UR - http://www.agu.org/journals/jb/ U6 - https://doi.org/10.1029/2008jb005788 SN - 0148-0227 ER - TY - JOUR A1 - Garcin, Yannick A1 - Schildgen, Taylor F. A1 - Acosta, Veronica Torres A1 - Melnick, Daniel A1 - Guillemoteau, Julien A1 - Willenbring, Jane A1 - Strecker, Manfred T1 - Short-lived increase in erosion during the African Humid Period BT - evidence from the northern Kenya Rift JF - Earth & planetary science letters N2 - The African Humid Period (AHP) between similar to 15 and 5.5 cal. kyr BP caused major environmental change in East Africa, including filling of the Suguta Valley in the northern Kenya Rift with an extensive (similar to 2150 km(2)), deep (similar to 300 m) lake. Interfingering fluvio-lacustrine deposits of the Baragoi paleo-delta provide insights into the lake-level history and how erosion rates changed during this time, as revealed by delta-volume estimates and the concentration of cosmogenic Be-10 in fluvial sand. Erosion rates derived from delta-volume estimates range from 0.019 to 0.03 mm yr(-1). Be-10-derived paleo-erosion rates at similar to 11.8 cal. kyr BP ranged from 0.035 to 0.086 mm yr(-1), and were 2.7 to 6.6 times faster than at present. In contrast, at similar to 8.7 cal. kyr BP, erosion rates were only 1.8 times faster than at present. Because Be-10-derived erosion rates integrate over several millennia; we modeled the erosion-rate history that best explains the 10Be data using established non-linear equations that describe in situ cosmogenic isotope production and decay. Two models with different temporal constraints (15-6.7 and 12-6.7 kyr) suggest erosion rates that were 25 to 300 times higher than the initial erosion rate (pre-delta formation). That pulse of high erosion rates was short (similar to 4 kyr or less) and must have been followed by a rapid decrease in rates while climate remained humid to reach the modern Be-10-based erosion rate of,similar to 0.013 mm yr(-1). Our simulations also flag the two highest Be-10-derived erosion rates at 11.8 kyr BP related to nonuniform catchment erosion. These changes in erosion rates and processes during the AHP may reflect a strong increase in precipitation, runoff, and erosivity at the arid-to-humid transition either at 15 or similar to 12 cal. kyr BP, before the landscape stabilized again, possibly due to increased soil production and denser vegetation. KW - northern Kenya Rift KW - Baragoi KW - paleo-delta KW - African Humid Period KW - erosion KW - Be-10 Y1 - 2017 U6 - https://doi.org/10.1016/j.epsl.2016.11.017 SN - 0012-821X SN - 1385-013X VL - 459 SP - 58 EP - 69 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Melnick, Daniel A1 - Yildirim, Cengiz A1 - Hillemann, Christian A1 - Garcin, Yannick A1 - Ciner, T. Attila A1 - Perez-Gussinye, Marta A1 - Strecker, Manfred T1 - Slip along the Sultanhani Fault in Central Anatolia from deformed Pleistocene shorelines of palaeo-lake Konya and implications for seismic hazards in low-strain regions JF - Geophysical journal international N2 - Central Anatolia is a low-relief, high-elevation region where decadal-scale deformation rates estimated from space geodesy suggest low strain rates within a stiff microplate. However, numerous Quaternary faults have been mapped within this low-strain region and estimating their slip rate and seismic potential is important for hazard assessments in an area of increasing infrastructural development. Here we focus on the Sultanhani Fault (SF), which constitutes an integral part of the Eskisehir-Cihanbeyli Fault System, and use deformed maximum highstand shorelines of palaeo-lake Konya to estimate tectonic slip rates at millennial scale. Some of these shorelines were previously interpreted as fault scarps, but we provide conclusive evidence for their erosional origin. We found that shoreline-angle elevations estimated from differential GPS profiles record vertical displacements of 10.2 m across the SF. New radiocarbon ages of lacustrine molluscs suggest 22.4 m of relative lake-level fall between 22.1 +/- 0.3 and 21.7 +/- 0.4 cal. kaBP, constraining the timing of abrupt abandonment of the highstand shoreline. Models of lithospheric rebound associated with regressions of the Tuz Golu and Konya palaeolakes predict only similar to 1 m of regional-scale uplift across the Konya Basin. Dislocation models of displaced shorelines suggest fault-slip rates of 1.5 and 1.8 mm yr(-1) for planar and listric fault geometries, respectively, providing reasonable results for the latter. We found fault scarps in the Nasuhpinar mudflat that likely represent the most recent ground-breaking rupture of the SF, with an average vertical displacement of 1.2 +/- 0.5 m estimated from 54 topographic profiles, equivalent to a M similar to 6.5-6.9 earthquake based on empirical scaling laws. If such events were characteristic during the ultimate 21 ka, a relatively short recurrence time of similar to 800-900 yr would be needed to account for the millennial slip rate. Alternatively, the fault scarp at Nasuhpinar might represent a larger earthquake requiring more frequent smaller events to account for the millennial rate. The relatively fast slip rate of the SF over the past 21 ka is unlikely to have persisted over longer timescales and might reflect spatiotemporal variations in deformation rates within kinematically-linked fault systems within Central Anatolia, or a transient perturbation to the local stress field or fault strength. Such perturbation might have been related to climatically controlled changes in surface and near-surface loads and by interactions among the different tectonic processes that have been proposed to drive the overall slow uplift and associated extension in the Central Anatolian Plateau. KW - Seismic cycle KW - Geomorphology KW - Continental neotectonics KW - Earthquake hazards KW - Tectonics and climatic interactions Y1 - 2017 U6 - https://doi.org/10.1093/gji/ggx074 SN - 0956-540X SN - 1365-246X VL - 209 SP - 1431 EP - 1454 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Jara-Munoz, Julius A1 - Melnick, Daniel A1 - Zambrano, Patricio A1 - Rietbrock, Andreas A1 - Gonzalez, Javiera A1 - Argandona, Boris A1 - Strecker, Manfred T1 - Quantifying offshore fore-arc deformation and splay-fault slip using drowned Pleistocene shorelines, Arauco Bay, Chile JF - Journal of geophysical research : Solid earth N2 - Most of the deformation associated with the seismic cycle in subduction zones occurs offshore and has been therefore difficult to quantify with direct observations at millennial timescales. Here we study millennial deformation associated with an active splay-fault system in the Arauco Bay area off south central Chile. We describe hitherto unrecognized drowned shorelines using high-resolution multibeam bathymetry, geomorphic, sedimentologic, and paleontologic observations and quantify uplift rates using a Landscape Evolution Model. Along a margin-normal profile, uplift rates are 1.3m/ka near the edge of the continental shelf, 1.5m/ka at the emerged Santa Maria Island, -0.1m/ka at the center of the Arauco Bay, and 0.3m/ka in the mainland. The bathymetry images a complex pattern of folds and faults representing the surface expression of the crustal-scale Santa Maria splay-fault system. We modeled surface deformation using two different structural scenarios: deep-reaching normal faults and deep-reaching reverse faults with shallow extensional structures. Our preferred model comprises a blind reverse fault extending from 3km depth down to the plate interface at 16km that slips at a rate between 3.0 and 3.7m/ka. If all the splay-fault slip occurs during every great megathrust earthquake, with a recurrence of similar to 150-200years, the fault would slip similar to 0.5m per event, equivalent to a magnitude similar to 6.4 earthquake. However, if the splay-fault slips only with a megathrust earthquake every similar to 1000years, the fault would slip similar to 3.7m per event, equivalent to a magnitude similar to 7.5 earthquake. KW - splay fault KW - marine terraces KW - Arauco Bay KW - TerraceM KW - fore arc KW - earthquake Y1 - 2017 U6 - https://doi.org/10.1002/2016JB013339 SN - 2169-9313 SN - 2169-9356 VL - 122 SP - 4529 EP - 4558 PB - American Geophysical Union CY - Washington ER - TY - GEN A1 - Garcin, Yannick A1 - Acosta, Veronica Torres A1 - Melnick, Daniel A1 - Guillemoteau, Julien A1 - Willenbring, Jane A1 - Strecker, Manfred T1 - Short-lived increase in erosion during the African Humid Period: Evidence from the northern Kenya Rift (vol 759, pg 58, 2017) T2 - Earth & planetary science letters Y1 - 2017 U6 - https://doi.org/10.1016/j.epsl.2017.07.027 SN - 0012-821X SN - 1385-013X VL - 474 SP - 528 EP - 528 PB - Elsevier CY - Amsterdam ER - TY - GEN A1 - Jara-Muñoz, Julius A1 - Melnick, Daniel A1 - Li, Shaoyang A1 - Socquet, Anne A1 - Cortés-Aranda, Joaquín A1 - Brill, Dominik A1 - Strecker, Manfred T1 - The cryptic seismic potential of the Pichilemu blind fault in Chile revealed by off-fault geomorphology T2 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - The first step towards assessing hazards in seismically active regions involves mapping capable faults and estimating their recurrence times. While the mapping of active faults is commonly based on distinct geologic and geomorphic features evident at the surface, mapping blind seismogenic faults is complicated by the absence of on-fault diagnostic features. Here we investigated the Pichilemu Fault in coastal Chile, unknown until it generated a Mw 7.0 earthquake in 2010. The lack of evident surface faulting suggests activity along a partly-hidden blind fault. We used off-fault deformed marine terraces to estimate a fault-slip rate of 0.52 ± 0.04 m/ka, which, when integrated with satellite geodesy suggests a 2.12 ± 0.2 ka recurrence time for Mw~7.0 normal-faulting earthquakes. We propose that extension in the Pichilemu region is associated with stress changes during megathrust earthquakes and accommodated by sporadic slip during upper-plate earthquakes, which has implications for assessing the seismic potential of cryptic faults along convergent margins and elsewhere. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1294 Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-574616 SN - 1866-8372 IS - 1294 ER - TY - JOUR A1 - Riedl, Simon A1 - Melnick, Daniel A1 - Mibei, Geoffrey K. A1 - Njue, Lucy A1 - Strecker, Manfred T1 - Continental rifting at magmatic centres BT - structural implications from the Late Quaternary Menengai Caldera, central Kenya Rift JF - Journal of the geological society N2 - The structural evolution of calderas in rifts helps to characterize the spatiotemporal relationships between magmatism, long wavelength crustal deformation and the formation of tectonic deformation zones along the rift axis. We document the structural characteristics of the c. 36 ka old Menengai Caldera located within a young zone of extension in the central Kenya Rift. Field mapping and high-resolution digital surface models show that NNE-striking Holocene normal faults perpendicular to the regional ESE-WNWextension direction dominate the interior sectors of the rift. Inside the caldera, these structures are overprinted by post-collapse doming and faulting of the magmatic centre, resulting in obliquely slipping normal faults bounding a resurgence horst. Radiocarbon dating of faulted units as young as 5 ka cal BP and the palaeo-shorelines of a lake formed during the African Humid Period in the Nakuru Basin indicate that volcanism and fault activity inside and in the vicinity of Menengai must have been sustained during the Holocene. Our analysis confirms that the caldera is located at the centre of an extending rift segment and suggests that other magmatic centres and young zones of faulting along the volcano-tectonic axis of the Kenya Rift may constitute nucleation points of faulting that ultimately foster future continental break-up. Y1 - 2020 U6 - https://doi.org/10.1144/jgs2019-021 SN - 0016-7649 SN - 2041-479X VL - 177 IS - 1 SP - 153 EP - 169 PB - Geological Soc. Publ. House CY - Bath ER - TY - JOUR A1 - Melnick, Daniel A1 - Garcin, Yannick A1 - Quinteros, Javier A1 - Strecker, Manfred A1 - Olago, Daniel A1 - Tiercelin, Jean-Jacques T1 - Steady rifting in northern Kenya inferred from deformed Holocene lake shorelines of the Suguta and Turkana basins JF - Earth & planetary science letters N2 - A comparison of deformation rates in active rifts over different temporal scales may help to decipher variations in their structural evolution, controlling mechanisms, and evolution of sedimentary environments through time. Here we use deformed lake shorelines in the Suguta and Turkana basins in northern Kenya as strain markers to estimate deformation rates at the 10(3)-10(4) yr time scale and compare them with rates spanning 10(1)-10(7) yr. Both basins are internally drained today, but until 7 to 5 kyr lake levels were 300 and 100 m higher, respectively, maintained by the elevation of overflow sills connecting them with the Nile drainage. Protracted high lake levels resulted in formation of a maximum highstand shoreline - a distinct geomorphic feature virtually continuous for several tens of kilometers. We surveyed the elevation of this geomorphic marker at 45 sites along >100 km of the rift, and use the overflow sills as vertical datum. Thin-shell elastic and thermomechanical models for this region predict up to similar to 10 m of rapid isostatic rebound associated with lake-level falls lasting until similar to 2 kyr ago. Holocene cumulative throw rates along four rift-normal profiles are 6.8-8.5 mm/yr, or 7.5-9.6 mm/yr if isostatic rebound is considered. Assuming fault dips of 55-65, inferred from seismic reflection profiles, we obtained extension rates of 3.2-6 mm/yr (including uncertainties in field measurements, fault dips, and ages), or 3.5-6.7 mm/yr considering rebound. Our estimates are consistent, within uncertainties, with extension rates of 4-5.1 mm/yr predicted by a modern plate-kinematic model and plate reconstructions since 3.2 Myr. The Holocene strain rate of 10(-15) s(-1) is similar to estimates on the similar to 10(6) yr scale, but over an order of magnitude higher than on the similar to 10(7) yr scale. This is coherent with continuous localization and narrowing of the plate boundary, implying that the lithospheric blocks limiting the Kenya Rift are relatively rigid. Increasing strain rate under steady extension rate suggests that, as the magnitude of extension and crustal thinning increases, the role of regional processes such as weakening by volcanism becomes dominant over far-field plate tectonics controlling the breakup process and the transition from continental rifting to oceanic spreading. KW - continental rifting KW - East Africa KW - lake shorelines KW - Holocene extension KW - isostatic rebound Y1 - 2012 U6 - https://doi.org/10.1016/j.epsl.2012.03.007 SN - 0012-821X VL - 331 IS - 10 SP - 335 EP - 346 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Garcin, Yannick A1 - Melnick, Daniel A1 - Strecker, Manfred A1 - Olago, Daniel A1 - Tiercelin, Jean-Jacques T1 - East African mid-Holocene wet-dry transition recorded in palaeo-shorelines of Lake Turkana, northern Kenya Rift JF - Earth & planetary science letters N2 - The 'wet' early to mid-Holocene of tropical Africa, with its enhanced monsoon, ended with an abrupt shift toward drier conditions and was ultimately replaced by a drier climate that has persisted until the present day. The forcing mechanisms, the timing, and the spatial extent of this major climatic transition are not well understood and remain the subject of ongoing research. We have used a detailed palaeo-shoreline record from Lake Turkana (Kenya) to decipher and characterise this marked climatic transition in East Africa. We present a high-precision survey of well-preserved palaeo-shorelines, new radiocarbon ages from shoreline deposits, and oxygen-isotope measurements on freshwater mollusk shells to elucidate the Holocene moisture history from former lake water-levels in this climatically sensitive region. In combination with previously published data our study shows that during the early Holocene the water-level in Lake Turkana was high and the lake overflowed temporarily into the White Nile drainage system. During the mid-Holocene (similar to 5270 +/- 300 cal. yr BP), however, the lake water-level fell by similar to 50 m, coeval with major episodes of aridity on the African continent. A comparison between palaeo-hydrological and archaeological data from the Turkana Basin suggests that the mid-Holocene climatic transition was associated with fundamental changes in prehistoric cultures, highlighting the significance of natural climate variability and associated periods of protracted drought as major environmental stress factors affecting human occupation in the East African Rift System. ( KW - East African Rift System KW - Lake Turkana KW - Palaeo-shorelines KW - African Humid Period KW - Holocene KW - Tectonic deformation Y1 - 2012 U6 - https://doi.org/10.1016/j.epsl.2012.03.016 SN - 0012-821X VL - 331 SP - 322 EP - 334 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Jara-Munoz, Julius A1 - Melnick, Daniel A1 - Strecker, Manfred T1 - TerraceM: A MATLAB (R) tool to analyze marine and lacustrine terraces using high-resolution topography JF - Geosphere N2 - High-resolution topographic data greatly facilitate the remote identification of geomorphic features, furnishing valuable information concerning surface processes and characterization of reference markers for quantifying tectonic deformation. Marine terraces have been used as long baseline geodetic markers of relative past sea-level positions, reflecting the interplay between vertical crustal movements and sea-level oscillations. Uplift rates may be determined from the terrace age and the elevation of its shoreline angle, a geomorphic feature that can be correlated with past sea-levels positions. A precise definition of the shoreline angle in time and space is essential to obtain reliable uplift rates with coherent spatial correlation. To improve our ability to rapidly assess and map shoreline angles at regional and local scales, we have developed TerraceM, a MATLAB (R) graphical user interface that allows the shoreline angle and its associated error to be estimated using high-resolution topography. TerraceM uses topographic swath profiles oriented orthogonally to the terrace riser. Four functions are included to analyze the swath profiles and extract the shoreline angle, from both staircase sequences of multiple terraces and rough coasts characterized by eroded remnants of emerged terrace surfaces. The former are measured by outlining the paleocliffs and paieo-platforms and finding their intersection by extrapolating linear regressions, whereas the latter are assessed by automatically detecting peaks of sea-stack tops and back-projecting them to the modern sea cliff. In the absence of rigorous absolute age determinations of marine terraces, their geomorphic age may be estimated using previously published diffusion models. Postprocessing functions are included to obtain first-order statistics of shoreline-angle elevations and their spatial distribution. TerraceM has the ability to process series of profiles from several sites in an efficient and structured workflow. Results may be exported in Google Earth and ESRI shapefile formats. The precision and accuracy of the method have been estimated from a case study at Santa Cruz, California, by comparing TerraceM results with published field measurements. The repeatability was evaluated using multiple measurements made by inexperienced users. TerraceM will improve the efficiency and precision of estimating shoreline-angle elevations in wave-cut terraces in both marine and lacustrine environments. Y1 - 2016 U6 - https://doi.org/10.1130/GES01208.1 SN - 1553-040X VL - 12 SP - 176 EP - 195 PB - American Institute of Physics CY - Boulder ER - TY - JOUR A1 - Ozsayin, Erman A1 - Ciner, T. Attila A1 - Rojay, F. Bora A1 - Dirik, R. Kadir A1 - Melnick, Daniel A1 - Fernandez-Blanco, David A1 - Bertotti, Giovanni A1 - Schildgen, Taylor F. A1 - Garcin, Yannick A1 - Strecker, Manfred A1 - Sudo, Masafumi T1 - Plio-Quaternary extensional tectonics of the Central Anatolian Plateau a case study from the Tuz Golu Basin, Turkey JF - Turkish journal of earth sciences = Türk yerbilimleri dergisi N2 - The Tuz Golu Basin is the largest sedimentary depression located at the center of the Central Anatolian Plateau, an extensive, low-relief region with elevations of ca. 1 km located between the Pontide and Tauride mountains. Presently, the basin morphology and sedimentation processes are mainly controlled by the extensional Tuz Golu Fault Zone in the east and the transtensional Inonu-Eskisehir Fault System in the west. The purpose of this study is to contribute to the understanding of the Plio-Quaternary deformation history and to refine the timing of the latest extensional phase of the Tuz Golu Basin. Field observations, kinematic analyses, interpretations of seismic reflection lines, and Ar-40/Ar-39 dating of a key ignimbrite layer suggest that a regional phase of NNW-SSE to NE-SW contraction ended by 6.81 +/- 0.24 Ma and was followed by N-S to NE-SW extension during the Pliocene-Quaternary periods. Based on sedimentological and chronostratigraphic markers, the average vertical displacement rates over the past 5 or 3 Ma with respect to the central part of Tuz Golu Lake are 0.03 to 0.05 mm/year for the fault system at the western flank of the basin and 0.08 to 0.13 mm/year at the eastern flank. Paleo-shorelines of the Tuz Golu Lake, vestiges of higher lake levels related to Quaternary climate change, are important strain markers and were formed during Last Glacial Maximum conditions as indicated by a radiocarbon age of 21.8 +/- 0.4 ka BP obtained from a stromatolitic crust. Geomorphic observations and deformed lacustrine shorelines suggest that the main strand of the Tuz Golu Fault Zone straddling the foothills of the Sereflikochisar-Aksaray range has not been active during the Holocene. Instead, deformation appears to have migrated towards the interior of the basin along an offshore fault that runs immediately west of Sereflikochisar Peninsula. This basinward migration of deformation is probably associated with various processes acting at the lithospheric scale, such as plateau uplift and/or microplate extrusion. KW - Central Anatolia KW - Tuz Golu Basin KW - orogenic plateau evolution KW - extensional tectonics KW - kinematic analysis KW - lake shoreline Y1 - 2013 U6 - https://doi.org/10.3906/yer-1210-5 SN - 1300-0985 VL - 22 IS - 5 SP - 691 EP - 714 PB - Tübitak CY - Ankara ER - TY - JOUR A1 - Riedl, Simon A1 - Melnick, Daniel A1 - Njue, Lucy A1 - Sudo, Masafumi A1 - Strecker, Manfred T1 - Mid-Pleistocene to recent crustal extension in the inner graben of the Northern Kenya Rift JF - Geochemistry, geophysics, geosystems N2 - Magmatic continental rifts often constitute nascent plate boundaries, yet long-term extension rates and transient rate changes associated with these early stages of continental breakup remain difficult to determine. Here, we derive a time-averaged minimum extension rate for the inner graben of the Northern Kenya Rift (NKR) of the East African Rift System for the last 0.5 m.y. We use the TanDEM-X science digital elevation model to evaluate fault-scarp geometries and determine fault throws across the volcano-tectonic axis of the inner graben of the NKR. Along rift-perpendicular profiles, amounts of cumulative extension are determined, and by integrating four new Ar-40/Ar-39 radiometric dates for the Silali volcano into the existing geochronology of the faulted volcanic units, time-averaged extension rates are calculated. This study reveals that in the inner graben of the NKR, the long-term extension rate based on mid-Pleistocene to recent brittle deformation has minimum values of 1.0-1.6 mm yr(-1), locally with values up to 2.0 mm yr(-1). A comparison with the decadal, geodetically determined extension rate reveals that at least 65% of the extension must be accommodated within a narrow, 20-km-wide zone of the inner rift. In light of virtually inactive border faults of the NKR, we show that extension is focused in the region of the active volcano-tectonic axis in the inner graben, thus highlighting the maturing of continental rifting in the NKR. KW - extensional tectonics KW - Kenya Rift KW - TanDEM-X DEM KW - DEM analysis KW - geochronology KW - normal faults Y1 - 2022 U6 - https://doi.org/10.1029/2021GC010123 SN - 1525-2027 VL - 23 IS - 3 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Georgieva, Viktoria A1 - Melnick, Daniel A1 - Schildgen, Taylor F. A1 - Ehlers, Todd A1 - Lagabrielle, Yves A1 - Enkelmann, Eva A1 - Strecker, Manfred T1 - Tectonic control on rock uplift, exhumation, and topography above an oceanic ridge collision: Southern Patagonian Andes (47 degrees S), Chile JF - Tectonics N2 - The subduction of bathymetric anomalies at convergent margins can profoundly affect subduction dynamics, magmatism, and the structural and geomorphic evolution of the overriding plate. The Northern Patagonian Icefield (NPI) is located east of the Chile Triple Junction at similar to 47 degrees S, where the Chile Rise spreading center collides with South America. This region is characterized by an abrupt increase in summit elevations and relief that has been controversially debated in the context of geodynamic versus glacial erosion effects on topography. Here we present geomorphic, thermochronological, and structural data that document neotectonic activity along hitherto unrecognized faults along the flanks of the NPI. New apatite (U-Th)/He bedrock cooling ages suggest faulting since 2-3 Ma. We infer the northward translation of an similar to 140 km long fore-arc sliver-the NPI block-results from enhanced partitioning of oblique plate convergence due to the closely spaced collision of three successive segments of the Chile Rise. In this model, greater uplift occurs in the hanging wall of the Exploradores thrust at the northern leading edge of the NPI block, whereas the Cachet and Liquine-Ofqui dextral faults decouple the NPI block along its eastern and western flanks, respectively. Localized extension possibly occurs at its southern trailing edge along normal faults associated with margin-parallel extension, tectonic subsidence, and lower elevations along the Andean crest line. Our neotectonic model provides a novel explanation for the abrupt topographic variations inland of the Chile Triple Junction and emphasizes the fundamental effects of local tectonics on exhumation and topographic patterns in this glaciated landscape. Y1 - 2016 U6 - https://doi.org/10.1002/2016TC004120 SN - 0278-7407 SN - 1944-9194 VL - 35 SP - 1317 EP - 1341 PB - American Geophysical Union CY - Washington ER -