2021年青海玛多M_(S)7.4地震精定位和发震构造初探

Precise location of the 2021 Maduo,Qinghai M_(S)7.4 earthquake and its seismogenic structure

2021年5月22日青海省果洛州玛多县发生M_(S)7.4地震。为探究本次地震的发震构造及余震分布特征,选取2021年5月1日—6月3日青海测震台网观测到的33°~36°N,97°~99.5°E空间范围内的地震观测报告,利用双差精定位方法进行双差精定位处理。重定位后整体残差平均减小了0.23,深度在5~25 km间随机分布。根据地震迁移方向和震区地质构造,认为本次地震的发震构造为昆仑山口—江错断裂,玛多—甘德东段受主震触发影响爆发一系列小震,两条断裂之间可能因为本次地震产生一定联系。本次地震产生新的断裂,突破了两条断裂之前的空区,连接到玛多—甘德断层,使两条断层交叉相连,形成新的断层构造。

An M_(S)7.4 earthquake occurred in Maduo County,Qinghai Province on May 22,2021.To explore the seismogenic structure of the earthquake and the distribution characteristics of aftershocks,this paper selected the seismic observation reports from Qinghai Seismic Network in a space range of 33-36°N,97-99.5°E from May 1 to June 3,2021.After double difference relocation,the overall residual was reduced by an average of 0.23,and the depth was randomly distributed within 5-25 km.According to the earthquake migration direction and local geological structure,it is believed that the seismogenic structure of the M_(S)7.4 earthquake is Kunlun Pass-Jiangcuo fault.A series of small earthquakes were triggered by the main earthquake and then occurred along the east section of Maduo-Gande fault.The earthquake may cause some connection between the two faults.A new fault was generated by the earthquake and then connected with the Maduo-Gande fault,so that the two faults crossed and connected,forming a new fault structure.