TY - JOUR A1 - Yuan, X. H A1 - Sobolev, Stephan Vladimir A1 - Kind, Rainer A1 - Oncken, Onno A1 - Bock, Günter A1 - Asch, Günter A1 - Schurr, B. A1 - Gräber, F. A1 - Rudloff, Alexander A1 - Hanka, W. A1 - Wylegalla, Kurt A1 - Tibi, R. A1 - Haberland, Christian A1 - Rietbrock, Andreas A1 - Giese, Peter A1 - Wigger, Peter A1 - Rower, P. A1 - Zandt, G. A1 - Beck, S. A1 - Wallace, T. A1 - Pardo, M. A1 - Comte, D. T1 - Subduction and collision processes in the Central Andes constrained by converted seismic phases Y1 - 2000 ER - TY - JOUR A1 - Schurr, B. A1 - Asch, Günter A1 - Rietbrock, Andreas A1 - Kind, Rainer A1 - Pardo, M. A1 - Heit, B. A1 - Monfret, T. T1 - Seismicity and average velocities beneath the Argentine Puna plateau Y1 - 1999 ER - TY - JOUR A1 - Rietbrock, Andreas A1 - Scherbaum, Frank T1 - Crustal scattering at the KTB from a combined microearthquake and receiver analysis Y1 - 1998 ER - TY - JOUR A1 - Rietbrock, Andreas A1 - Scherbaum, Frank T1 - The GIANT analysis system (Graphical Interaktive Aftershock Network Toolbox) Y1 - 1998 ER - TY - JOUR A1 - Oncken, Onno A1 - Luschen, Ewald A1 - Mechie, James A1 - Sobolev, Stephan Vladimir A1 - Schulze, Albrecht A1 - Gaedicke, Christoph A1 - Grunewald, Steffen A1 - Bribach, Jens A1 - Asch, Günter A1 - Giese, Peter A1 - Wigger, Peter A1 - Schmitz, Michael A1 - Lueth, Stefan A1 - Scheuber, Ekkehard A1 - Haberland, Christian A1 - Rietbrock, Andreas A1 - Götze, Hans-Jürgen A1 - Brasse, Heinrich A1 - Patzwahl, Regina A1 - Chong, Guillermo A1 - Wilke, Hans-Gerhard A1 - Gonzalez, Gabriel A1 - Jensen, Arturo A1 - Araneda, Manuel A1 - Vieytes, Hugo A1 - Behn, Gerardo A1 - Martinez, Eloy T1 - Seismic reflection image revealing offset of Andean subduction-zone earthquake locations into oceanic mantle Y1 - 1999 ER - TY - JOUR A1 - Martin, Sebastian A1 - Haberland, Christian A1 - Rietbrock, Andreas T1 - Forearc decoupling of guided waves in the Chile-Peru subduction zone N2 - The structure and alterations of subducted oceanic lithosphere ( e. g., thickness and seismic velocity of oceanic crust) can be obtained by analyzing guided seismic waves generated by earthquakes within the slab (Wadati- Benioff zone). In northern Chile prominent secondary phases from intermediate-depth seismicity, observed in the forearc region can be interpreted as guided waves. For the observation of guided waves it is usually required to have stations close to the wave guide, a fact which is not directly given for forearc stations in subduction zone environments. With the help of finite difference simulations we model the decoupling mechanism of guided waves at the contact between the descending oceanic plate and the upper plate crust where the wave guide is opened due to the equalization of seismic velocities. Provided that suited stations are available, this mechanism allows for the use of intermediate depth seismicity to study the shallow subduction zone structure ( <= 100 km depth) Y1 - 2005 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 - JOUR A1 - Haberland, Christian A1 - Rietbrock, Andreas A1 - Schurr, B. A1 - Brasse, Heinrich T1 - Coincident anomalies of seismic attenuation and electrical resistivity beneath the southern Bolivian Altiplano plateau N2 - Reassessment of local earthquake data from the ANCORP seismological network allowed the calculation of 3D attenuation (Q(p)) tomographic images of crust and upper mantle beneath the southern Bolivian Altiplano around 21degrees S. The images reveal a low-Q(p) middle and lower crust and a moderate-Q(p) upper mantle beneath the southern Altiplano. Beneath the recent magmatic arc, Q(p) is not significantly decreased at this latitude. The distribution of crustal Q(p) coincides with the variation of electrical resistivity, thus limiting the possible mechanisms causing the anomalies. Our findings support the hypothesis that partial melts in middle and lower crust beneath the Altiplano are present on a large scale. We see no evidence for a shallow asthenosphere beneath the southern Altiplano Y1 - 2003 SN - 0094-8276 ER - TY - JOUR A1 - Haberland, Christian A1 - Rietbrock, Andreas A1 - Lange, Dietrich A1 - Bataille, Klaus A1 - Hofmann, S. T1 - Interaction between forearc and oceanic plate at the south-central Chilean margin as seen in local seismic data JF - Geophysical research letters N2 - We installed a dense, amphibious, temporary seismological network to study the seismicity and structure of the seismogenic zone in southern Chile between 37° and 39°S, the nucleation area of the great 1960 Chile earthquake. 213 local earthquakes with 14.754 onset times were used for a simultaneous inversion for the 1‐D velocity model and precise earthquake locations. Relocated artificial shots suggest an accuracy of the earthquake hypocenter of about 1 km (horizontally) and 500 m (vertically). Crustal events along trench‐parallel and transverse, deep‐reaching faults reflect the interseismic transpressional deformation of the forearc crust due to the subduction of the Nazca plate. The transverse faults seems to accomplish differential lateral stresses between subduction zone segments. Many events situated in an internally structured, planar seismicity patch at 20 to 40 km depth near the coast indicate a stress concentration at the plate's interface at 38°S which might in part be induced by the fragmented forearc structure. Y1 - 2006 U6 - https://doi.org/10.1029/2006GL028189 SN - 0094-8276 VL - 33 IS - 23 PB - Union CY - Washington ER - TY - JOUR A1 - Giese, Peter A1 - Graeber, F. A1 - Haberland, Christian A1 - Rietbrock, Andreas A1 - Schurr, B. A1 - Asch, Günter T1 - La sismicidad en los Andes Centrales - una revision Y1 - 1999 SN - 987-97770-1-8 ER - TY - JOUR A1 - Collings, R. A1 - Rietbrock, Andreas A1 - Lange, Dietrich A1 - Tilmann, F. A1 - Nippress, Stuart A1 - Natawidjaja, D. T1 - Seismic anisotropy in the sumatra subduction zone JF - Journal of geophysical research : Solid earth N2 - An important tool for understanding deformation occurring within a subduction zone is the measurement of seismic anisotropy through observations of shear wave splitting (SWS). In Sumatra, two temporary seismic networks were deployed between December 2007 and February 2009, covering the fore arc between the fore-arc islands to the back arc. We use SKS and local SWS measurements to determine the type, amount, and location of anisotropy. Local SWS measurements from the fore-arc islands exhibit trench-parallel fast directions which can be attributed to shape preferred orientation of cracks/fractures in the overriding sediments. In the Sumatran Fault region, the predominant fast direction is fault/trench parallel, while in the back-arc region it is trench perpendicular. The trench-perpendicular measurements exhibit a positive correlation between delay time and raypath length in the mantle wedge, while the fault-parallel measurements are similar to the fault-parallel fast directions observed for two crustal events at the Sumatran Fault. This suggests that there are two layers of anisotropy: one due to entrained flow within the mantle wedge and a second layer within the overriding crust due to the shear strain caused by the Sumatran Fault. SKS splitting results show a NNW-SSE fast direction with delay times of 0.8-3.0s. The fast directions are approximately parallel to the absolute plate motion of the subducting Indo-Australian Plate. The small delay times exhibited by the local SWS (0.05-0.45s), in combination with the large SKS delay times, suggest that the anisotropy generating the teleseismic SWS is dominated by entrained flow in the asthenosphere below the slab. KW - Sumatra KW - Anisotropy KW - Shear wave splitting KW - Subduction zone KW - Mantle rheology Y1 - 2013 U6 - https://doi.org/10.1002/jgrb.50157 SN - 2169-9313 SN - 2169-9356 VL - 118 IS - 10 SP - 5372 EP - 5390 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Collings, R. A1 - Lange, Dietrich A1 - Rietbrock, Andreas A1 - Tilmann, F. A1 - Natawidjaja, D. A1 - Suwargadi, B. A1 - Miller, M. A1 - Saul, Joschim T1 - Structure and seismogenic properties of the Mentawai segment of the Sumatra subduction zone revealed by local earthquake traveltime tomography JF - Journal of geophysical research : Solid earth N2 - On 12 September 2007, an M-w 8.4 earthquake occurred within the southern section of the Mentawai segment of the Sumatra subduction zone, where the subduction thrust had previously ruptured in 1833 and 1797. Traveltime data obtained from a temporary local seismic network, deployed between December 2007 and October 2008 to record the aftershocks of the 2007 event, was used to determine two-dimensional (2-D) and three-dimensional (3-D) velocity models of the Mentawai segment. The seismicity distribution reveals significant activity along the subduction interface and within two clusters in the overriding plate either side of the forearc basin. The downgoing slab is clearly distinguished by a dipping region of high Vp (8.0 km/s), which can be a traced to similar to 50 km depth, with an increased Vp/Vs ratio (1.75 to 1.90) beneath the islands and the western side of the forearc basin, suggesting hydrated oceanic crust. Above the slab, a shallow continental Moho of less than 30 km depth can be inferred, suggesting that the intersection of the continental mantle with the subducting slab is much shallower than the downdip limit of the seismogenic zone despite localized serpentinization being present at the toe of the mantle wedge. The outer arc islands are characterized by low Vp (4.5-5.8 km/s) and high Vp/Vs (greater than 2.0), suggesting that they consist of fluid saturated sediments. The very low rigidity of the outer forearc contributed to the slow rupture of the M-w 7.7 Mentawai tsunami earthquake on 25 October 2010. Y1 - 2012 U6 - https://doi.org/10.1029/2011JB008469 SN - 2169-9313 SN - 2169-9356 VL - 117 IS - 3 PB - American Geophysical Union CY - Washington ER -