近日，中国地震局地震研究所刘刚的团队在研究青藏高原东部鲜水河断裂带磨西—石棉段滑动速率与震间耦合中取得新进展。2024年2月20日出版的《大地测量与地球动力学》发表了这项成果。

研究人员在磨西—石棉段建立了一系列近场全球卫星导航系统(GNSS)站，以提高用于地震间运动参数反演的观测数据的空间分辨率。研究利用GNSS观测约束下的弹性螺旋位错模型，估计磨西—石棉段的滑动速率为10.9±1.0 mm/yr，锁定深度为15.7±6.2 km。此外，研究利用块体—位错模型反演了康定—磨西—石棉段的震间断裂带耦合。

结果表明，从康定至石棉段，闭锁深度逐渐加深。2022年地震同震破裂发生在康定—磨西—石棉段的高耦合区内，表明该事件的破裂运动学可能受震间形变控制。1786年以来，泸定地震破裂带内累积的地震矩在[1.42-3.40]× 10¹⁹Nm之间，明显大于2022年事件释放的地震矩。因此，研究人员推断，自1786年以来，泸定地震仅释放了原破裂带内累积能量的一部分，表明2022年的事件并未在磨西—石棉段引发完全破裂。因此，该地区仍有很大的地震危险。

据了解，2022年9月5日，泸定6.8级地震发生在鲜水河断裂带磨西—石棉段，与1786年磨西地震的历史破裂带重合。其孕震环境为理解地震的发生机制和未来的危险性提供了基础。

附：英文原文

Title: Slip rate and interseismic coupling along the Moxi-Shimian segment of the Xianshuihe fault, Eastern Qinghai-Xizang Plateau

Author: Xinyu Zhao, Gang Liu, Zhaosheng Nie, Wei Xiong, Wei Chen, Mu Lin, Dijin Wang, Qi Li, Jiansheng Yu, Dongzhen Wang, Pengfei Yu

Issue&Volume: 2024/02/20

Abstract: On September 5, 2022, the Luding M6.8 earthquake occurred in the Moxi-Shimian segment of the Xianshuihe fault, coinciding with the historical ruptured zone of the 1786 Moxi earthquake. Its seismogenic environment provides a foundation for comprehending the mechanism of the earthquake and its future hazard. In the Moxi-Shimian segment, we establish a series of near-field Global Navigation Satellite Systems (GNSS) stations to enhance the spatial resolution of observational data for the inversion of the interseismic kinematic parameters. In this study, with an elastic screw dislocation model constrained by GNSS observations, the slip rate of the Moxi-Shimian segment is estimated to be 10.9 ± 1.0 mm/yr, while the locking depth is 15.7 ± 6.2 km. Additionally, we utilize a block-dislocation model to invert the interseismic fault coupling along the Kangding-Moxi-Shimian segment. The result indicates a gradual deepening of the locking depth along the section from Kangding to Shimian. The coseismic rupture of the 2022 event occurred within the high coupling regions in the Kangding-Moxi-Shimian segment, which indicates that the rupture kinematics in this event might be controlled by the interseismic deformation. The seismic moment accumulated within the ruptured zone of the Luding earthquake since 1786 ranges in [1.42–3.40] × 10¹⁹ N m, which is significantly greater than the seismic moment released during the 2022 event. As a result, we infer that the Luding earthquake released only a portion of the accumulated energy within the original rupture zone since 1786, indicating that the 2022 event has not caused a complete rupture in the Moxi-Shimian segment. Consequently, there remains a substantial seismic hazard in this area.

DOI: 10.1016/j.geog.2024.01.004

Source: https://www.sciencedirect.com/science/article/pii/S1674984724000156