An active extensional deformation example: 19 May 2011 Simav earthquake (<i>Mw</i>= 5.8), Western Anatolia, Turkey

Demirci, Alper; Özden, Süha; Bekler, Tolga; Kalafat, Doğan; Pınar, Ali

doi:10.1088/1742-2132/12/4/552

Cited by 9 publications

(8 citation statements)

References 83 publications

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“…Published focal mechanisms from several sources consistently indicate WNW‐ESE normal faulting with nodal plane dips in the range 30°–60° (Table ). Although minor cracking was observed in two locations west of Simav, approximately coincident with the north dipping Simav fault, there were no clear indications of primary surface rupturing [ Zülfikar et al , ; Demirci et al , ]. Aftershocks relocated with the double‐difference technique do not align along a clear rupture plane [ Görgün , ; Demirci et al , ], and hence, the dip direction of the causative fault is unclear.…”

Section: The 19 May 2011 Simav Earthquakementioning

confidence: 99%

“…Although minor cracking was observed in two locations west of Simav, approximately coincident with the north dipping Simav fault, there were no clear indications of primary surface rupturing [ Zülfikar et al , ; Demirci et al , ]. Aftershocks relocated with the double‐difference technique do not align along a clear rupture plane [ Görgün , ; Demirci et al , ], and hence, the dip direction of the causative fault is unclear. Body waveform modeling by Yolsal‐Çevikbilen et al [] indicates a centroid depth of ∼9 km, also consistent with the lack of surface ruptures.…”

Section: The 19 May 2011 Simav Earthquakementioning

confidence: 99%

“…By contrast, Görgün [] and Demirci et al [] obtained aftershock depth ranges of 2–24 km and 2–16 km, respectively, using the double‐difference relocation technique [ Waldhauser and Ellsworth , ]. This algorithm is more sensitive to the velocity model, since the relative location problem is not separated from the absolute relocation problem and there is little emphasis on the uncertainties.…”

Section: Regional Seismicity From Calibrated Earthquake Relocationsmentioning

confidence: 99%

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

et al. 2016

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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.

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Section: The 19 May 2011 Simav Earthquakementioning

confidence: 99%

Section: The 19 May 2011 Simav Earthquakementioning

confidence: 99%

Section: Regional Seismicity From Calibrated Earthquake Relocationsmentioning

confidence: 99%

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

et al. 2016

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“…Before the May 19, 2011, mainshock (M w 5.9), there were three moderate (magnitude greater than 6.0) earthquakes that occurred in the study area in the twentieth century: May 2, 1928 (M 6.2) earthquake [11], June 25, 1944 (M 6.0) earthquake [11], and March 28, 1970 (M 7.1) Gediz earthquake [12] (Figure 1). The distribution of seismicity cannot be associated with the system of faults in the region, which has been of interest to many researchers in geology, geochemistry, and paleoseismicity [9,[13][14][15][16][17][18][19]. A detailed study in western Anatolia, published by Akyol et al [20], in 2006 observed lower than average crustal seismic velocities that may be associated with high crustal temperature.…”

Section: Introductionmentioning

confidence: 99%

“…Yolsal-Çelikbilen et al [21] indicated a centroid depth of about 9 km. Demirci et al [18] did a study on rupture analysis, moment tensor (MT) inversion, damage distribution, and failure stress analysis. They observed a 70-to 80-degree dipping WNW-ESE normal fault, after the May 19, 2011, Simav mainshock, as the result of the active extension regime in western Turkey.…”

Section: Introductionmentioning

confidence: 99%

Seismicity, focal mechanism, and stress tensor analysis of the Simav region, western Turkey

Mutlu

2020

Open Geosciences

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This study focuses on the seismicity and stress inversion analysis of the Simav region in western Turkey. The latest moderate-size earthquake was recorded on May 19, 2011 (Mw 5.9), with a dense aftershock sequence of more than 5,000 earthquakes in 6 months. Between 2004 and 2018, data from earthquake events with magnitudes greater than 0.7 were compiled from 86 seismic stations. The source mechanism of 54 earthquakes with moment magnitudes greater than 3.5 was derived by using a moment tensor inversion. Normal faults with oblique-slip motions are dominant being compatible with the NE-SW extension direction of western Turkey. The regional stress field is assessed from focal mechanisms. Vertically oriented maximum compressional stress (σ1) is consistent with the extensional regime in the region. The σ1 and σ3 stress axes suggest the WNW-ESE compression and the NNE-SSW dilatation. The principal stress orientations support the movement direction of the NE-SW extension consistent with the mainly observed normal faulting motions.

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Large Stress Release During Normal-Faulting Earthquakes in Western Turkey Supported by Broadband Ground Motion Simulations

Tanırcan

Yamanaka

Özel

2019

Pure Appl. Geophys.

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An active extensional deformation example: 19 May 2011 Simav earthquake (Mw= 5.8), Western Anatolia, Turkey

Cited by 9 publications

References 83 publications

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

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

Seismicity, focal mechanism, and stress tensor analysis of the Simav region, western Turkey

Large Stress Release During Normal-Faulting Earthquakes in Western Turkey Supported by Broadband Ground Motion Simulations

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