知识与财富的链接
2021年5月22日,青海省玛多县发生了7.4级地震,该地震发生在巴颜喀拉地块北部边界东昆仑断裂带以南约70 km,属于块体内部断裂带地震.根据中国大陆构造环境监测网络提供资料,距离震源30多公里的玛多台站记录到东西向永久位移约25 cm.同时,InSAR也观测到明显的形变场,升轨和降轨的最大相对形变量分别约1.87 m和2.32 m.为了解释这些大地测量观测数据,本文利用该地震的三个断层滑动模型,基于不同地球模型的地震位错理论,计算同震变形场,并分别与GNSS观测数据和InSAR视线向形变量对比分析,结果显示基于InSAR数据反演的断层滑动模型产生的位移场与球形地球模型的理论计算结果最为吻合.进一步,利用较优断层模型计算2021年青海玛多7.4级地震的理论同震位移、大地水准面、重力和应变等变化,该结果为玛多地震的GNSS和重力观测的解释提供理论参考依据.
The Madoi M7.4 earthquake occurred on May 22, 2021, in Madoi County, Qinghai Province. It is located at ~70 km south of the East Kunlun fault zone on the northern boundary of the Bayan Har block. So it belongs to the intra-block fault zone earthquake. According to the data provided by the China Continental Tectonic Environment Monitoring Network, ~25 cm permanent east-west displacement is recorded at the Madoi Station, which is more than 30 km away from the epicenter. Meanwhile, the InSAR also observes obvious deformation field, with the maximum relative LOS (Line of Sight) of ascending and descending about 1.87 m and 2.
32 m, respectively. In order to interpret these geodetic observation data, we use seismic dislocation theory of different Earth models based on three fault slip models to calculate the coseismic deformation field and compare results with GNSS observation and InSAR LOS deformation. The result indicates the displacement field generated by the fault slip model which is inversed by InSAR data is good agreement with the theoretical calculation with the spherical earth model. Furthermore, we use the better fault model to calculate the theoretical coseismic displacement, geoid, gravity and strain changes of the 2021 Qinghai Madoi M7.4 earthquake. The results provide a theoretical basis for GNSS and gravity observation interpretation of Madoi earthquake.
