@article{ErbelloDoelessoMelnickZeilingeretal.2022, author = {Erbello Doelesso, Asfaw and Melnick, Daniel and Zeilinger, Gerold and Bookhagen, Bodo and Pingel, Heiko and Strecker, Manfred}, title = {Geomorphic expression of a tectonically active rift-transfer zone in southern Ethiopia}, series = {Geomorphology : an international journal on pure and applied geomorphology}, volume = {403}, journal = {Geomorphology : an international journal on pure and applied geomorphology}, publisher = {Elsevier Science}, address = {Amsterdam [u.a.]}, issn = {0169-555X}, doi = {10.1016/j.geomorph.2022.108162}, pages = {20}, year = {2022}, abstract = {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.}, language = {en} } @article{RiedlMelnickNjueetal.2022, author = {Riedl, Simon and Melnick, Daniel and Njue, Lucy and Sudo, Masafumi and Strecker, Manfred}, title = {Mid-Pleistocene to recent crustal extension in the inner graben of the Northern Kenya Rift}, series = {Geochemistry, geophysics, geosystems}, volume = {23}, journal = {Geochemistry, geophysics, geosystems}, number = {3}, publisher = {American Geophysical Union}, address = {Washington}, issn = {1525-2027}, doi = {10.1029/2021GC010123}, pages = {25}, year = {2022}, abstract = {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.}, language = {en} } @article{JaraMunozMelnickLietal.2022, author = {Jara-Mu{\~n}oz, Julius and Melnick, Daniel and Li, Shaoyang and Socquet, Anne and Cort{\´e}s-Aranda, Joaqu{\´i}n and Brill, Dominik and Strecker, Manfred}, title = {The cryptic seismic potential of the Pichilemu blind fault in Chile revealed by off-fault geomorphology}, series = {Nature Communications}, volume = {13}, journal = {Nature Communications}, publisher = {Springer Nature}, address = {London}, issn = {2041-1723}, doi = {10.1038/s41467-022-30754-1}, pages = {13}, year = {2022}, abstract = {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.}, language = {en} } @misc{JaraMunozMelnickLietal.2022, author = {Jara-Mu{\~n}oz, Julius and Melnick, Daniel and Li, Shaoyang and Socquet, Anne and Cort{\´e}s-Aranda, Joaqu{\´i}n and Brill, Dominik and Strecker, Manfred}, title = {The cryptic seismic potential of the Pichilemu blind fault in Chile revealed by off-fault geomorphology}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1294}, issn = {1866-8372}, doi = {10.25932/publishup-57461}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-574616}, pages = {13}, year = {2022}, abstract = {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.}, language = {en} } @article{FreislebenJaraMunozMelnicketal.2021, author = {Freisleben, Roland and Jara-Munoz, Julius and Melnick, Daniel and Miguel Martinez, Jose and Strecker, Manfred}, title = {Marine terraces of the last interglacial period along the Pacific coast of South America (1 degrees N-40 degrees S)}, series = {Earth system science data : ESSD}, volume = {13}, journal = {Earth system science data : ESSD}, number = {6}, publisher = {Copernics Publications}, address = {Katlenburg-Lindau}, issn = {1866-3508}, doi = {10.5194/essd-13-2487-2021}, pages = {2487 -- 2513}, year = {2021}, abstract = {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).}, language = {en} } @article{RacanoJaraMunozCosentinoetal.2020, author = {Racano, Simone and Jara-Munoz, Julius and Cosentino, Domenico and Melnick, Daniel}, title = {Variable quaternary uplift along the Southern Margin of the Central Anatolian Plateau inferred from modeling Marine Terrace sequences}, series = {Tectonics}, volume = {39}, journal = {Tectonics}, number = {12}, publisher = {American Geophysical Union}, address = {Washington}, issn = {0278-7407}, doi = {10.1029/2019TC005921}, pages = {22}, year = {2020}, abstract = {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.}, language = {en} } @article{RiedlMelnickMibeietal.2020, author = {Riedl, Simon and Melnick, Daniel and Mibei, Geoffrey K. and Njue, Lucy and Strecker, Manfred}, title = {Continental rifting at magmatic centres}, series = {Journal of the geological society}, volume = {177}, journal = {Journal of the geological society}, number = {1}, publisher = {Geological Soc. Publ. House}, address = {Bath}, issn = {0016-7649}, doi = {10.1144/jgs2019-021}, pages = {153 -- 169}, year = {2020}, abstract = {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.}, language = {en} } @article{deGelderFernandezBlancoMelnicketal.2019, author = {de Gelder, Gino and Fernandez-Blanco, David and Melnick, Daniel and Duclaux, Guillaume and Bell, Rebecca E. and Jara-Munoz, Julius and Armijo, Rolando and Lacassin, Robin}, title = {Lithospheric flexure and rheology determined by climate cycle markers in the Corinth Rift}, series = {Scientific reports}, volume = {9}, journal = {Scientific reports}, publisher = {Nature Publ. Group}, address = {London}, issn = {2045-2322}, doi = {10.1038/s41598-018-36377-1}, pages = {12}, year = {2019}, abstract = {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.}, language = {en} } @article{JaraMunozMelnickPedojaetal.2019, author = {Jara-Munoz, Julius and Melnick, Daniel and Pedoja, Kevin and Strecker, Manfred}, title = {TerraceM-2: A MatlabR (R) Interface for Mapping and Modeling Marine and Lacustrine Terraces}, series = {Frontiers in Earth Science}, volume = {7}, journal = {Frontiers in Earth Science}, publisher = {Frontiers Research Foundation}, address = {Lausanne}, issn = {2296-6463}, doi = {10.3389/feart.2019.00255}, pages = {18}, year = {2019}, abstract = {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.}, language = {en} } @article{MelnickHillemannJaraMunozetal.2019, author = {Melnick, Daniel and Hillemann, Christian and Jara Mu{\~n}oz, Julius and Garrett, Ed and Cortes-Aranda, Joaquin and Molina, Diego and Tassara, Andr{\´e}s and Strecker, Manfred}, title = {Hidden Holocene Slip Along the Coastal El Yolki Fault in Central Chile and Its Possible Link With Megathrust Earthquakes}, series = {Journal of geophysical research : Solid earth}, volume = {124}, journal = {Journal of geophysical research : Solid earth}, number = {7}, publisher = {American Geophysical Union}, address = {Washington}, issn = {2169-9313}, doi = {10.1029/2018JB017188}, pages = {7280 -- 7302}, year = {2019}, abstract = {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.}, language = {en} }