Source mechanism of the 23 October, 2011, Van (Turkey) earthquake (M w = 7.1) and aftershocks with its tectonic implications

Abstract

This study has investigated the rupture process of the 23 October, 2011, Van (Turkey) earthquake (M w = 7.1) by using inversion of teleseismic waveform analysis and its tectonic implications. Focal parameters of the main shock and 21 aftershocks were obtained by using the rst motion polarities of regional P-waves. The rst results for the source rupture process were derived from broadband teleseismic P-waves. The main outcomes of the analysis are: (a) the main rupture is located around the initial break point, and the maximum slip amount was 3.6 m; (b) the size of the main fault plane area was about 40 km in length and 20 km in width, the duration of rupture was approximately 19 seconds and the seismic moment of the earthquake was estimated to be 5.53 × 10 19 N m (M w = 7.1); (c) the rupture gradually expanded near the hypocenter and propagated both northeast and southwest, but mainly to the southwest. Tectonic implications of the earthquake were de ned by eld observations. The 23 October, 2011, Van earthquake occurred on a main thrust fault plane trending NE-SW between Lake Van and Lake Erçek located in the East Anatolian compressional province. This main fault plane and the secondary structural elements were generated by a continental-continental collision taking place in a region located 200 km north of the the Bitlis-Zagros Suture Zone.

Patterns and mechanisms of coseismic and postseismic slips of the 2011 M W 7.1 Van (Turkey) earthquake revealed by multi-platform synthetic aperture radar interferometry

“…Additionally, a second shallow slip patch is seen at the southwest of the fault plane, which is similar to another two published seismic models [e.g. Irmak et al 2012;Fielding et al, 2013] although it does not appear in the two published InSAR models (Elliott et al, 2013;Fielding et al, 2013). As mentioned in Section 2.4, a simplified fault plane was assumed in the coseismic modelling by neglecting the slightly curved and stepped geometry of the fault trace.…”

“…Although the depth of the maximum slip varies in the published slip models, the major slip patch is observed with a maximum magnitude of ~ 4 m in the deeper part followed by a small shallow event in the seismic waveform inversions (Fielding et al, 2013;Irmak et al, 2012), which is also supported by two-point source modelling (Zahradník and Sokos, 2014).…”

“…As presented in Figure 4(e), the best-fit model suggests that the maximum slip and distributed patterns are consistent with those from the elastic half-space Model A, both having RMS of 5 mm for InSAR observations. The average rake angle of the patches with slip > 1.5 m is ~79°, which is closer to the seismic solution (Irmak et al, 2012) relative to an average rake angle of 86° determined from the elastic half-space model.…”

“…There have been several seismic solutions published for the 2011 Van earthquake (Ashtari Jafari, 2013;Fielding et al, 2013;Irmak et al, 2012;Utkucu, 2013;Zahradnik and Sokos, 2013), most suggesting that the major rupture propagated along the dip direction from its origin to 10 seconds with a maximum slip of ~4 m near the epicentre, and another small amount of energy was released from 10-18 seconds (Fielding et al, 2013;Irmak et al, 2012). The entire rupture lasted for less than 20 seconds.…”

“…Several papers have investigated the coseismic deformation, focal mechanisms and aftershocks of this event (Altiner et al, 2013;Elliott et al, 2013;Fielding et al, 2013;Irmak et al, 2012;Moro et al, 2014;Utkucu, 2013;Zahradník and Sokos, 2014). The mechanisms of the mainshock determined from geodetic observations and seismic waveforms are generally consistent.…”