Spatial and Temporal Variation of b-value in East China
The seismic data of ML≥2.0 from 1980 to October 2023 in East China were selected,and the b-value was calculated using the maximum likelihood method. The spatial and temporal changes of b-value and the spatial distribution characteristics of Δb in the study area in recent ten years were analyzed,and the following understandings were obtained:(1) In terms of time-varying characteristics,most earthquakes occur in the period when b-value drops,and b-value rises after earthquakes,and there are a few other cor-responding situations;(2) In terms of spatial characteristics,most moderate earthquakes occur in low b-values and their boundary regions;(3) The stress level in the border areas between Anhui and neighboring provinces (especially the border areas between Henan,Hubei and Anhui) and central Hubei have increased in recent ten years,and the risk of strong earthquakes should be continuously paid attention to in the future.
East China areamaximum likelihood methodb-valueΔb-valuespatio-temporal variation characteristics