scholarly journals A new insight into the sources of the 1733DC-M7.8 earthquake on the Xiaojiang fault zone, southeastern Tibet

2022 ◽  
Author(s):  
Yun Zhou ◽  
Li-Sheng Xu ◽  
Zhengyang Pan ◽  
Ming Hao ◽  
Chun-Lai Li
2020 ◽  
Vol 60 (1) ◽  
Author(s):  
Andrej Gosar

A recent slip-rate of an active fault is a very important seismotectonic parameter, but not easy to determine. Idrija fault, 120 km long, is a prominent geomorphologic feature with large seismogenic potential, still needed to be researched. Measurements of tectonic micro-displacements can provide insight into its recent activity. The Učja valley extends transversally to the Idrija fault and was therefore selected for the installation of TM 71 extensometer. Measurements on the crack within its inner fault zone are conducted from the year 2004. In 14 years of observations a systematic horizontal displacements with average rate of 0.21 mm/year and subordinate vertical displacements of 0.06 mm/year were established, proving the activity of this fault. An overview of methods of displacement measurements related to active faults and of newer interdisciplinary investigations of the Idrija fault is given. Displacement rates are beside for geodynamic interpretations important for improvement of seismotectonic models and thus for better seismic hazard assessment.


2021 ◽  
Author(s):  
Yijian Zhou ◽  
Han Yue ◽  
Shiyong Zhou ◽  
Lihua Fang ◽  
Yun Zhou ◽  
...  

2021 ◽  
Vol 64 (4) ◽  
pp. SE439
Author(s):  
T Serkan Irmak ◽  
Mustafa Toker ◽  
Evrim Yavuz ◽  
Erman Şentürk ◽  
Muhammed Ali Güvenaltın

In this study, we investigated the main features of the causative fault of the 24 January 2020, Mw 6.8 Elazığ earthquake (Turkey) using seismological and geodetic data sets to provide new insight into the East Anatolian Fault Zone (EAFZ). We first constrained the co-seismic surface deformation and the rupture geometry of the causative fault segment using Interferometric Synthetic Aperture Radar (InSAR) interferograms (Sentinel-1A/B satellites) and teleseismic waveform inversion, respectively. Also, we determined the centroid moment tensor (CMT) solutions of focal mechanisms of the 27 aftershocks using the regional waveform inversion method. Finally, we evaluated the co-seismic slip distribution and the CMT solutions of the causative fault as well as of adjacent segments using the 27 focal solutions of the aftershocks, superimposed on the surface deformation pattern. The CMT solution of the 24 January 2020Elazığ earthquake reveals a pure strike-slip focal mechanism, consistent with the structural pattern and left-lateral motion of the EAFZ. The rupture process of the Elazığ event indicated that the rupture is started at 12 km around the hypocenter, and then propagated bilaterally along the NE-SW but mainly toward the southwest. The rupture slip has initially propagated toward the southwest (first 10 s) and northeast (4 s), and again toward the southwest (9 s). Maximum displacement is calculated as 1.3 m about 20 km southwest of the hypocenter at 6 km depth (centroid depth). The rupture stopped to down-dip around 20 km depth toward the southwest. The distribution of the slip vectors indicates that the rupture continued mostly through a normal oblique movement. Most of the moment release was released SW of the hypocenter and the rupture reached up to around 50 km. The focal mechanisms of analyzed 27 aftershocks show strike-slip, but mostly normal and normal oblique-slip faulting with an orientation of the tensional axes (NNE-SSW), indicating a normal oblique-slip, “transtensional” stress regime, parallel-subparallel to the strike of the EAFZ, consistent with SW-rupture directivity and co- seismic deformation pattern. Finally, based on the co-seismic surface deformation compatible with the distributional pattern of normal focal solutions, normal and normal oblique-slip focals of the aftershocks evidence the rupture-parallel pull-apart basin activation as a segment boundary of the left-lateral strike-slip movement of the EAFZ.


2008 ◽  
Vol 51 (9) ◽  
pp. 1248-1258 ◽  
Author(s):  
HongLin He ◽  
Yasutaka Ikeda ◽  
YuLin He ◽  
Masayoshi Togo ◽  
Jie Chen ◽  
...  

2020 ◽  
Author(s):  
Yijian Zhou ◽  
Shiyong Zhou ◽  
Hao Zhang ◽  
Yu Hou ◽  
Weilai Pei ◽  
...  

<p>Xiaojiang Fault (XJF) lies at the southeastern edge of the rhombic Sichuan-Yunnan block, and has an extent for over 400km from Qiaojia to Shanhua district. The Sichuan-Yunnan block experiences clockwise rotation and southwestward escaping from the Tibetan Plateau, producing complex fault geometry and seismicity pattern. The strong variation along fault segments provides a special opportunity to study the relationship between fault zone properties and seismicity pattern. However, the fine structure of XJF remains unknown due to the sparse observational stations.</p><p>Seismic data has its unique advantage of resolving fault zone properties at depth. We deployed 48 broad-band seismometers along XJF in order to capture detailed seismicity patterns. Our seismic network covers the northern and middle part of XJF, with an average aperture of 20km; the continuous observation from 2015 to 2019 guarantees enough data volume. We detected about 12,000 earthquakes by STA/LTA phase picking and association, and augmented the detection to over 50,000 events with template matching. The relocated catalog has lateral and vertical resolution of 500m and 1km, respectively; the magnitude of completeness (Mc) reaches ML0.3</p><p>This high-resolution catalog depicts detailed 3D fault geometry. The seismicity shows clustered lateral distribution, with the clusters’ depth extension ranging from 20km at northern to 35km at southern segments. Unmapped orthogonal faults on northern XJF are illuminated by seismicity, which matches orthogonal topography characteristics. Repeating events are detected from 8 seismicity clusters, under a threshold of 5 repeating families, indicating a creeping slip mode, while the separated low-seismicity segments exhibit a high locking rate. Taking advantage of the high detectability, we got reliable b-value estimation for different segments of XJF. The low-b regions correlate well with the margins of locking patches, which points to a high stress concentration. Velocity structure extracted from ambient noise and fault zone head wave present similar spatial variation, which further proved the seismicity pattern. The high heterogeneous characteristics of XJF may produce stress barriers, preventing future earthquake rupture from propagating to a large scale. </p>


2006 ◽  
Vol 422 (1-4) ◽  
pp. 159-173 ◽  
Author(s):  
José Miguel Martínez-Martínez ◽  
Guillermo Booth-Rea ◽  
José Miguel Azañón ◽  
Federico Torcal

2013 ◽  
Vol 56 (4) ◽  
pp. 400-410
Author(s):  
WU Jian-Ping ◽  
YANG Ting ◽  
WANG Wei-Lai ◽  
MING Yue-Hong ◽  
ZHANG Tian-Zhong

2016 ◽  
Vol 13 (6) ◽  
pp. 1096-1106 ◽  
Author(s):  
Tian-tao Li ◽  
Xiang-jun Pei ◽  
Run-qiu Huang ◽  
Long-de Jin

2012 ◽  
Vol 544-545 ◽  
pp. 93-102 ◽  
Author(s):  
Wang Shifeng ◽  
Jiang Guiguo ◽  
Xu Tiande ◽  
Tian Yuntao ◽  
Zheng Dewen ◽  
...  

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