利用反投影技术快速测定中强震矩震级及破裂过程——以2023年9月9日摩洛哥MW6.9地震为例

Rapid Estimation of the Moment Magnitude and Rupture Process of Moderate and Large Earthquakes Using Back-projection——A Case of Morocco MW6.9 Earthquake on September 9, 2023

摘要:

利用远场台阵反投影技术可以较少地依赖先验经验,于震后快速获得震源破裂过程时空分布特征,并据此估算矩震级。本文使用美国阿拉斯加宽频带台阵记录到的远场直达P波数据,基于反投影方法,对2023年9月9日摩洛哥M_W6.9地震震源破裂过程及震级进行分析。结果显示,地震破裂走向以NE-SW向为主,地震能量在10～20s集中在震中距10km范围内释放,与震源机制解和震中区亚特拉斯山脉走向基本一致。震源破裂持续时间结合在全球分布均匀的GSN台网记录到的P波最大位移数据,在震后约15min即可快速估算出本次地震矩震级为M_W7.0,与中国地震台网中心和美国地质调查局发布震级基本一致。

Abstract:

The back-projection method is a useful tool that allows for the rapid determination of energy distribution in both space and time,without relying heavily on prior experience. In this paper,we utilized vertical components of teleseismic P-wave data recorded by the Alaska array to image the rupture process of the M_W6.9 Morocco earthquake that occurred on September 9th,2023. The results indicate that the trend of rupture of earthquake was predominantly in NE-SW,and the energy release occurred within 10km of the epicenter at 10～20 seconds,which is consistent with the focal mechanism and the trend of the Atlas Mountains. Combined with the maximum amplitude of P-wave displacement waveforms recorded by the globally distributed GSN network,the moment magnitude of the earthquake is quickly estimated as 7.0 within 15mins after the origin time,which is basically consistent with the magnitude released by China Earthquake Networks Center and United States Geological Survey.