2021年3月19日西藏比如M_S 6.1地震总结

2021年3月19日西藏比如M_(S )6.1地震发生在班戈—安多地区的安多盆地南缘断裂附近,震源机制解反演结果显示,本次地震为近东西走向断层产生正断兼走滑型错动的结果,与区域构造特征一致;截止至4月15日,地震序列跟踪发现,主震与余震震级差为1.4,主震释放能量占序列的98.96%,表明6.1级主震释放了此次地震序列的绝大部分能量。通过总结地震周边的地震活动异常发现,震前存在6级地震空区及3级地震条带交汇等异常,同时存在地震发生率、b值、D值、RTL值、地震调制比等地震学参数异常,地球物理观测统计显示,震中300 km范围内无地球物理观测测项。此外,比如地震打破了大陆地区长时间的5级以上地震平静,对后续6级地震的发生具有一定预测意义。

Summary of the Biru MS 6.1 earthquake in Tibet on March 19, 2021

On March 19, 2021, the Biru M_S 6.1 earthquake occurred near the fault on the southern margin of the Amdo Basin in the Bange-Amdo region. The focal mechanism solution shows the strike direction of the seismogenic fault of the Biru earthquake is near east-west and the fault movement is characterized by tension and strike-slip, which is consistent with the regional structural characteristics. The analysis of the Biru earthquake sequence reveals that the magnitude difference between the mainshock and the largest aftershock is 1.4 and almost 98.96% of the entire energy of the earthquake sequence is released by the mainshock. The seismic anomalies before the Biru earthquake are systematically analyzed. An M_S ≥ 6.0 seismic gap, two intersecting M_S 3.0 seismic belts, several seismic parameter anomalies including earthquake occurrence rate, b value, D value, RTL, and seismic modulation ratio have been found before the mainshock. As to geophysical anomalies, there is no geophysical observation within 300 km of the epicenter. In addition, the Biru earthquake broke the long-term seismic quiescence of earthquakes above M_S 5.0 in Chinese mainland, which can predict the occurrence of subsequent large earthquakes to some extent.