TY - JOUR A1 - Rößler, Dirk A1 - Rumpker, Georg A1 - Krüger, Frank T1 - Ambiguous moment tensors and radiation patterns in anisotropic media with applications to the modeling of earthquake mechanisms in W-Bohemia N2 - Anisotropic material properties are usually neglected during inversions for source parameters of earthquakes. In general anisotropic media, however, moment tensors for pure-shear sources can exhibit significant non-double-couple components. Such effects may be erroneously interpreted as an indication for volumetric changes at the source. Here we investigate effects of anisotropy on seismic moment tensors and radiation patterns for pure-shear and tensile-type sources. Anisotropy can significantly influence the interpretation of the source mechanisms. For example, the orientation of the slip within the fault plane may affect the total seismic moment. Also, moment tensors due to pure- shear and tensile faulting can have similar characteristics depending on the orientation of the elastic tensor. Furthermore, the tensile nature of an earthquake can be obscured by near-source anisotropic properties. As an application, we consider effects of inhomogeneous anisotropic properties on the seismic moment tensor and the radiation patterns of a selected type of micro-earthquakes observed in W-Bohemia. The combined effects of near-source and along- path anisotropy cause characteristic amplitude distortions of the P, S1 and S2 waves. However, the modeling suggests that neither homogeneous nor inhomogeneous anisotropic properties alone can explain the observed large non-double-couple components. The results also indicate that a correct analysis of the source mechanism, in principle, is achievable by application of anisotropic moment tensor inversion Y1 - 2004 SN - 0039-3169 ER - TY - JOUR A1 - Weber, Michael H. A1 - Wicks, Chuck A1 - Krüger, Frank A1 - Jahnke, Gunnar A1 - Baumann, M. T1 - Reply to comment on "Asymmetric radiation of seismic waves from an atoll : Nuclear tests in French Polynesia" by A. Douglas Y1 - 2000 ER - TY - JOUR A1 - Brechner, Stefan A1 - Klinge, Klaus A1 - Krüger, Frank A1 - Plenefisch, Thomas T1 - Backazimuthal variations of splitting parameters of teleseismic SKS phases observed at the broadband stations in Germany Y1 - 1998 ER - TY - JOUR A1 - Weber, Michael H. A1 - Wicks, Chuck A1 - Krüger, Frank A1 - Jahnke, Gunnar A1 - Schlittenhardt, Jörg T1 - Asymmetric radiation of seismic waves from an atoll : nuclear tests in French Polynesia Y1 - 1998 ER - TY - JOUR A1 - Krüger, Frank A1 - Grosser, H. A1 - Baumbach, M. A1 - Berckhemer, Hans T1 - The Erzincan (Turkey) earthquake (Ms 6.8) of March 13, 1992 and its aftershock sequence Y1 - 1998 ER - TY - JOUR A1 - Scherbaum, Frank A1 - Krüger, Frank A1 - Weber, Michael H. T1 - Double beam imaging : mapping lower mantle heterogeneities using combinations of source and receiver arrays Y1 - 1997 ER - TY - JOUR A1 - Freybourger, Marion A1 - Krüger, Frank A1 - Achauer, Ulrich T1 - A 22 degree long seismic profile for the study of the top D" Y1 - 1999 ER - TY - JOUR A1 - Friedrich, Andree A1 - Krüger, Frank A1 - Klinge, Klaus T1 - Ocean generated microseismic noise located with the Graefenberg array Y1 - 1998 ER - TY - JOUR A1 - Knapmeyer-Endrun, Brigitte A1 - Krüger, Frank A1 - Legendre, C. P. A1 - Geissler, Wolfram H. T1 - Tracing the influence of the trans-european suture zone into the mantle transition zone JF - Earth & planetary science letters N2 - Cratons with their thick lithospheric roots can influence the thermal structure, and thus the convective flow, in the surrounding mantle. As mantle temperatures are hard to measure directly, depth variations in the mantle transition zone (MTZ) discontinuities are often employed as a proxy. Here, we use a large new data set of P-receiver functions to map the 410 km and 660 km discontinuities beneath the western edge of the East European Craton and adjacent Phanerozoic Europe across the most fundamental lithospheric boundary in Europe, the Trans-European Suture Zone (TESZ). We observe significantly shorter travel times for conversions from both MTZ discontinuities within the craton, caused by the high velocities of the cratonic root. By contrast, the differential travel time across the MTZ is normal to only slightly raised. This implies that any insulating effect of the cratonic keel does not reach the MTZ. In contrast to earlier observations in Siberia, we do not find any trace of a discontinuity at 520 km depth, which indicates a rather dry MTZ beneath the western edge of the craton. Within most of covered Phanerozoic Europe, the MTZ differential travel time is remarkably uniform and in agreement with standard Earth models. No widespread thermal effects of the various episodes of Caledonian and Variscan subduction that took place during the amalgamation of the continent remain. Only more recent tectonic events, related to Alpine subduction and Quarternary volcanism in the Eifel area, can be traced. While the East European craton shows no distinct imprint into the MTZ, we discover the signature of the TESZ in the MTZ in the form of a linear region of about 350 km width with a 1.5 s increase in differential travel time, which could either be caused by high water content or decreased temperature. Taking into account results of recent S-wave tomographies, raised water content in the MTZ cannot be the main cause for this observation. Accordingly, we explain the increase, equivalent to a 15 km thicker MTZ, by a temperature decrease of about 80 K. We discuss two alternative models for this temperature reduction, either a remnant of subduction or an indication of downwelling due to small-scale, edge-driven convection caused by the contrast in lithospheric thickness across the TESZ. Any subducted lithosphere found in the MTZ at this location is unlikely to be related to Variscan subduction along the TESZ, though, as Eurasia has moved significantly northward since the Variscan orogeny. KW - mantle transition zone KW - Trans-European Suture Zone KW - East European Craton KW - edge-driven convection KW - receiver functions Y1 - 2013 U6 - https://doi.org/10.1016/j.epsl.2012.12.028 SN - 0012-821X SN - 1385-013X VL - 363 SP - 73 EP - 87 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Kinscher, Jannes A1 - Krüger, Frank A1 - Woith, H. A1 - Lühr, B. G. A1 - Hintersberger, E. A1 - Irmak, T. Serkan A1 - Baris, S. T1 - Seismotectonics of the Armutlu peninsula (Marmara Sea, NW Turkey) from geological field observation and regional moment tensor inversion JF - Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth N2 - The Armutlu peninsula, located in the eastern Marmara Sea, coincides with the western end of the rupture of the 17 August 1999, Izmit M-W 7.6 earthquake which is the penultimate event of an apparently westward migrating series of strong and disastrous earthquakes along the NAFZ during the past century. We present new seismotectonic data of this key region in order to evaluate previous seismotectonic models and their implications for seismic hazard assessment in the eastern Marmara Sea. Long term kinematics were investigated by performing paleo strain reconstruction from geological field investigations by morphotectonic and kinematic analysis of exposed brittle faults. Short term kinematics were investigated by inverting for the moment tensor of 13 small to moderate recent earthquakes using surface wave amplitude spectra. Our results confirm previous models interpreting the eastern Marmara Sea Region as an active transtensional pull-apart environment associated with significant NNE-SSW extension and vertical displacement. At the northern peninsula, long term deformation pattern did not change significantly since Pliocene times contradicting regional tectonic models which postulate a newly formed single dextral strike slip fault in the Marmara Sea Region. This area is interpreted as a horsetail splay fault structure associated with a major normal fault segment that we call the Waterfall Fault. Apart from the Waterfall Fault, the stress strain relation appears complex associated with a complicated internal fault geometry, strain partitioning, and reactivation of pre-existing plane structures. At the southern peninsula, recent deformation indicates active pull-apart tectonics constituted by NE-SW trending dextral strike slip faults. Earthquakes generated by stress release along large rupture zones seem to be less probable at the northern, but more probable at the southern peninsula. Additionally, regional seismicity appears predominantly driven by plate boundary stresses as transtensional faulting is consistent with the southwest directed far field deformation of the Anatolian plate. (C) 2013 Elsevier B.V. All rights reserved. KW - Seismotectonics KW - Moment tensor inversion KW - Brittle fault analysis KW - Morphotectonics KW - North Anatolian Fault Zone (NAFZ) KW - Marmara Sea Y1 - 2013 U6 - https://doi.org/10.1016/j.tecto.2013.07.016 SN - 0040-1951 SN - 1879-3266 VL - 608 IS - 46 SP - 980 EP - 995 PB - Elsevier CY - Amsterdam ER -