山东长清M4.1地震序列重定位、发震构造及震级偏差

Sequence Relocation,Seismogenic Structure and Magnitude Deviation of the Shandong Changqing M4.1 Earthquake

基于山东数字地震台网震相观测数据,采用双差定位方法对2020年山东长清M4.1地震序列中可定位地震进行重定位;采用CAP波形反演方法,获得了主震的震源机制解,进而分析本次地震可能的发震构造。结果表明,长清M4.1地震序列分布收敛明显,线性条带特征清晰,余震沿NW向延伸;地震错动类型为走滑兼正断型,近NS方向拉张。针对此次长清地震震级偏差问题,经过对不同震中距台站的震级标定测试,得出地震速报时选用台站策略:选用震中距近且包围震中好的5~6个台站确定震中位置,用震中距在100~200 km内的10~20个台站确定震级,时间允许的情况下尽可能地多用台站参与定位。

Based on the seismic phase data from Shandong digital seismic network,the double difference positioning method was used to analyze those relocatable earthquakes in M4.1 earthquake sequence in Changqing,Shandong province in 2020.CAP waveform inversion method was used to calculate the focal mechanism solution of the main earthquake.The possible seismogenic structure of these earthquakes is discussed.The results show that the seismic sequence distribution converges obviously,the linear band feature is clear,the aftershock extends along the northwest direction.The focal mechanism shows that the earthquake dislocation type is comprised of both strike-slip and normal fault,which stretched in the north-south direction.Through the calibration test of this earthquake,we can preliminarily obtain the earthquake quick report strategy:select 5~6 stations close to the epicenter to determine the location of the epicenter,and use 10~20 stations within 100~200 kilometers to determine the magnitude.If time permits,more stations should be involved in the positioning as much as possible.