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Normal faulting in the Simav graben of western Turkey reassessed with calibrated earthquake relocations

Karasözen, E.; Nissen, E.; Bergman, E.A.; Johnson, K.L.; Walters, R.J.

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Authors

E. Karasözen

E. Nissen

E.A. Bergman

K.L. Johnson

R.J. Walters



Abstract

Western Turkey has a long history of large earthquakes, but the responsible faults are poorly characterized. Here we reassess the past half century of instrumental earthquakes in the Simav-Gediz region, starting with the 19 May 2011 Simav earthquake (Mw 5.9), which we image using interferometric synthetic aperture radar and regional and teleseismic waveforms. This event ruptured a steep, planar normal fault centered at 7–9 km depth but failed to break the surface. However, relocated main shock and aftershock hypocenters occurred beneath the main slip plane at 10–22 km depth, implying rupture initiation in areas of low coseismic slip. These calibrated modern earthquakes provide the impetus to relocate and reassess older instrumental events in the region. Aftershocks of the 1970 Gediz earthquake (Mw 7.1) form a narrow band, inconsistent with source models that invoke low-angle detachment faulting, and may include events triggered dynamically by the unilateral main shock rupture. Epicenters of the 1969 Demirci earthquakes (Mw 5.9, 6.0) are more consistent with slip on the south dipping Akdağ fault than the larger, north dipping Simav fault. A counterintuitive aspect of recent seismicity across our study area is that the largest event (Mw 7.1) occurred in an area of slower extension and indistinct surface faulting, yet ruptured the surface, while recent earthquakes in the well-defined and more rapidly extending Simav graben are smaller (Mw <6.0) and failed to produce surface breaks. Though our study area bounds a major metamorphic core complex, there is no evidence for involvement of low-angle normal faulting in any of the recent large earthquakes.

Citation

Karasözen, E., Nissen, E., Bergman, E., Johnson, K., & Walters, R. (2016). Normal faulting in the Simav graben of western Turkey reassessed with calibrated earthquake relocations. Journal of Geophysical Research. Solid Earth, 121(6), 4553-4574. https://doi.org/10.1002/2016jb012828

Journal Article Type Article
Acceptance Date May 25, 2016
Online Publication Date Jun 30, 2016
Publication Date Jun 30, 2016
Deposit Date Jul 19, 2016
Publicly Available Date Mar 29, 2024
Journal Journal of Geophysical Research. Solid Earth
Print ISSN 2169-9313
Electronic ISSN 2169-9356
Publisher American Geophysical Union
Peer Reviewed Peer Reviewed
Volume 121
Issue 6
Pages 4553-4574
DOI https://doi.org/10.1002/2016jb012828

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Copyright Statement
Karasözen, E., E. Nissen, E. A. Bergman, K. L. Johnson, and R. J. Walters (2016), Normal faulting in the Simav graben of western Turkey reassessed with calibrated earthquake relocations, Journal of Geophysical Research: Solid Earth, 121, 4553–4574, 10.1002/2016JB012828 (DOI). To view the published open abstract, go to http://dx.doi.org and enter the DOI.




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