Rupture Process of the 23 October 2011 Mw7.1 Van Earthquake in Eastern Turkey by Joint Inversion of Teleseismic, GPS and Strong-Motion Data

Abstract

On October 23, 2011, a strong earthquake (Mw=7.1) struck Van (Eastern Turkey) region and its surrounding areas at 10:41:22 UTC (hereafter referred to as Van earthquake), causing severe damage to the source region. Several studies have been carried out on the focal mechanism, seismic moment, focal depth, and rupture model of this earthquake. However, there are still significant differences in the moment release, focal depth and slip asperities among these models. Since most of these models only used a single dataset to investigate the source parameters, the reliability of these results is still a concern. In order to make clear the uncertainties and provide a reliable detailed rupture model for the main shock, we investigate the rupture process of the Van earthquake by a joint inversion of teleseismic broadband seismograms, near field static GPS displacement records and strong motion data. The inversion results indicate that the main shock is dominated by a thrust slip with a small part of left-lateral strike-slip component below the hypocenter. The rupture initiated at a focal depth of 16 km and propagated to the surface with a relatively low average rupture velocity of ~ 1.8 km/s, suggesting that the major energy of the earthquake could be released in long period band, which is the main reason why the seismic moments inverted by long period or static signals are higher than those obtained by short period data. Most of slip occurred around the hypocenter with the maximum slip of more than 3.3 m, and the associated * Yong Zheng, corresponding author, Email: zhengyong@whigg.ac.cn static stress drop is ~3 MPa. The total seismic moment of the whole fault is 5.76×10 19 N·m, and most energy was released in the first 20 s, which is in the variation range of the released rupture models. The major slip is concentrated in the deeper depth, and extends to the depth around 25 km; meanwhile, the rupture in the ground surface is quite small, which explains why only weak ruptures observed at the surface caused by such a strong earthquake.

Rupture features of the 2016 Mw 6.2 Norcia earthquake and its possible relationship with strong seismic hazards

“…[, ]. There are substantial benefits to jointly inverting seismic and geodetic data, which are as shown by lots of previous studies [e.g., Shao et al ., ; Wei et al ., ; Fielding et al ., ; Yue et al ., ; Liu et al ., ; Grandin et al ., ]. The geodetic data sets, such as GPS and interferometric synthetic aperture radar (InSAR), provide strong constraints on the spatial distribution of the whole slip pattern, while the seismic data sets can provide good constraints on the temporal evolution of the rupture migrating, so these two types of data sets are complementary to each other during the joint inversion.…”

Seismogenic Structure of the 2014 M6.5 Ludian Earthquake From Three‐Dimensional Joint Inversion of Magnetotelluric Data and Seismic Arrival Times

“…There are two major NE trending thrust faults near the Ludian earthquake area, the Zhaotong fault (ZTF) and the Lianfeng fault (LFF) (Figure 1b), which developed on the basis of the NE trending thrust nappe tectonic belt in Cenozoic and constitute the tectonic boundary between the Daliangshan Sub‐block and the Yangtze platform. Based on estimates of the mainshock focal mechanism (Liu et al., 2014; X. W. Xu et al., 2014; Y. Zhang et al., 2014), the spatial distribution of aftershocks, regional seismic structure (X. Y. Zhao & Sun, 2014), and strong ground motion records (Jin et al., 2014), it is assumed that the Ludian earthquake did not occur on these two thrust faults, but on the Baogunao‐Xiaohe fault (BG‐XHF) in NNW direction, which is a secondary strike‐slip fault of the NE‐trending ZT‐LF fault system. These three faults all belong to the Xiaojiang fault (XJF) system (X. W. Xu et al., 2014).…”

“…Many studies have explored the Ludian earthquake from different perspectives, including the seismotectonic background (Jin et al., 2014; X. W. Xu et al., 2014), the focal location (F. Li et al., 2020; W. L. Wang et al., 2014; X. W. Xu et al., 2014), the seismogenic mechanism (Fu et al., 2015; Liu et al., 2014; Xie et al., 2015; X. W. Xu et al., 2014; Y. Zhang et al., 2014), the seismic velocity structure (Cao et al., 2021; Riaz et al., 2017; C. Z. Wang et al., 2021; X. Y. Zhao & Sun, 2014), and the electrical resistivity structure (Cai et al., 2017). Studies of the focal mechanism and rupture distribution show that most of the coseismic slip of the Ludian earthquake is concentrated at a depth of less than 10 km, which increases ground shakings and enhances the destructive force of the earthquake (Xie et al., 2015; Y. Zhang et al., 2014).…”

“…There are two major NE trending thrust faults near the Ludian earthquake area, the Zhaotong fault (ZTF) and the Lianfeng fault (LFF) (Figure 1b), which developed on the basis of the NE trending thrust nappe tectonic belt in Cenozoic and constitute the tectonic boundary between the Daliangshan Sub-block and the Yangtze platform. Based on estimates of the mainshock focal mechanism (Liu et al, 2014;X. W. Xu et al, 2014;, the spatial distribution of aftershocks, regional seismic structure (X. Y.…”

“…L. Wang et al, 2014;X. W. Xu et al, 2014), the seismogenic mechanism (Fu et al, 2015;Liu et al, 2014;Xie et al, 2015;X. W. Xu et al, 2014;, the seismic velocity structure (Cao et al, 2021;Riaz et al, 2017;C.…”