Study on the characteristics of b-value anomalies before and after moderate and strong earthquakes in western Sichuan
Based on the earthquake catalog provided by the Sichuan Seismrc Station,the maximum likelihood method was used to conduct b-value temporal and spatial scanning of moderate and strong earthquakes in the western Sichuan and analyze the b-value anomaly characteristics before and after the earthquakes,such as Ya'an MS 7.0 on April 20,2013,Kangding MS 6.3 on November 22,2014,Lushan MS 6.1 on June 1,2022,and Luding MS 6.8 on September 5,2022.The results show that:① The seismicity near the seismic-generating area was relatively calm for a period of time before the four earthquakes.② The time scanning results of b-value show that:b-value is distributed in the range of 0.553 to 1.134,with an average value of 0.879.Before the four earthquakes,the b-value is in a low state,and shows an upward trend after the earthquakes.Before the earthquakes,the b-values of the seismic source area were below the average,and all show the abnormal characteristics of declining,low peak and rising.
b-valuemaximum likelihood methodearthquake predictionbefore and after the earthquakeMc