Anormalies of b-value Changes before M≥4.0 Earthquake in Tangshan Old Seismic Region
We select the data of earthquake catalogue from January 2009 to December 2022 in Tangshan old seismic region to calculate the b-value.The lattice searching method is used to determine the abnormal area with a significantly decrease in b-value(≥20％),the time variation characteristics of the b-value in this area are analyzed,the risk of M≥4.0 earthquakes in the area is studied based on the b-value spatiotemporal variation characteris-tics.The research has found that 7 M≥4.0 earthquakes occurred at or near the edges of areas with significantly decrease in b-values in the Tangshan old earthquake area,which indicates that areas with high regional stress are high-risk areas for earthquake occurrence.According to the time changes of b-values in the abnormal area,most of the 7 M≥4.0 earthquakes(groups)experienced a decrease in b-values from half a year to one year before the earthquake,which also reflects the gradual accumulation of stress in the abnormal area.The b-value decrease in time and space has indicative significance for the study and judgment of M≥4.0 earthquakes in the Tangshan old seismic region.
Tangshan old seismic regionAnomalous characteristicsb-valueLattice searching
NETL
NSTL
万方数据
