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- Title
青藏高原中部日干配错断裂第四纪活动特征及 2020 年 7 月 23 日西藏尼玛 Mw6.4 地震发震构造分析.
- Authors
刘富财; 潘家伟; 孙知明; 刘栋梁; 卢海建; 郑 勇; 王世广; 白明坤; Marie-Luce CHEVALIER; 张 蕾; 曹 勇
- Abstract
The Riganpei Co fault (RPCF), located to the north of the Bangong Co-Nujiang suture (BNS), is a ENE-WSW striking left-lateral fault that belongs to the V-shaped conjugate strike-slip fault system of central Tibet. It plays an important role in accommodating coeval east-west extension and NS-trending shortening in the interior of the Tibetan Plateau. Two large earthquakes (M>6) occurred on January 9, 2008 and July 23, 2020 near the southwestern end and northeastern normal splay of the fault, respectively. Therefore, determining the Late Quaternary activity of the fault and its relationship with regional large earthquakes is essential to the better understanding of the active deformation behavior and its influence on regional earthquake nucleation. In this paper, the authors studied the Late Quaternary slip-rate along the RPCF and its tectonic-geomorphologic characteristics based on the interpretation of high-resolution satellite images and field surveys. The seismogenic fault of the Mw6.4 Nima earthquake on July 23, 2020 was also discussed. The results indicate that the RPCF has a significant linear distribution characteristics. It cut through the Quaternary geological and geomorphic units, forming a series of typical fault related tectonic geomorphologic phenomena. The RPCF strikes NEE 60°~80° for ~360 km, with a long-term cumulative displacement of 14~15 km. The late Pleistocene slip rate of the sinistral RPCF is about 0.2~0.3 mm/a, which is significantly lower than the values along the dextral faults south of the BNS. This implies that the mechanisms and dynamics are most likely different in the north and in the south of the BNS. The 2020 Nima Mw6.4 earthquake resulted from recent activity along the Yibug Caka graben, and the seismogenic fault was most likely the normal fault bounding its eastern side. The results obtained by the authors provide a new reference for the deeper understanding of the EW extensional deformation process and the mechanism of large earthquakes in central Tibet during the Quaternary.
- Publication
Acta Geoscientica Sinica, 2022, Vol 43, Issue 2, p173
- ISSN
1006-3021
- Publication type
Article
- DOI
10.3975/cagsb.2021.010402