Abstract:Using the Moya method on the waveform data recorded by the Gansu digital seismic network, we calculate the stress drop of 157 earthquakes with ML≥2.0, occurring in Menyuan area before the January 21, 2016 Menyuan MS6.4 earthquake. The results show that the stress drop ranges from 0.02 MPa to 10.86 MPa with an average value of 1.67 MPa. The earthquakes with high stress drop are mainly distributed between Huangcheng-Shuangta and Lenglongling fault zones, and the area is in harmony with the active area of moderate-strong earthquakes. It is found from analyzing the temporal distribution of stress drop that obvious stress high drop values appear before the MS5.1 earthquake. The stress drop of earthquakes gradually decreases and are generally at a low level after the MS5.1 earthquake. About half a year before the MS6.4 earthquake, twice high-value anomalies of the monthly mean values of stress drop appear, showing some relationship with Menyuan earthquake.
ZUO Kezhen,CHEN Jifeng,PU Ju et al. Study of the Spatial and Temporal Distribution Characteristics of StressDrop before the January 21, 2016 MS6.4 Menyuan Earthquake[J]. jgg, 2018, 38(6): 629-633.