Relationship Between Earthquake b‐Values and Crustal Stresses in a Young Orogenic Belt

Abstract

AbstractIt has been reported that earthquake b‐values decrease linearly with the differential stresses in the continental crust and subduction zones. Here we report a regression‐derived relation between earthquake b‐values and crustal stresses using the Anderson fault parameter (Aϕ) in a young orogenic belt of Taiwan. This regression relation is well established by using a large and complete earthquake catalog for Taiwan. The data set consists of b‐values and Aϕ values derived from relocated earthquakes and focal mechanisms, respectively. Our results show that b‐values decrease linearly with the Aϕ values at crustal depths with a high correlation coefficient of −0.9. Thus, b‐values could be used as stress indicators for orogenic belts. However, the state of stress is relatively well correlated with the surface geological setting with respect to earthquake b‐values in Taiwan. Temporal variations in the b‐value could constitute one of the main reasons for the spatial heterogeneity of b‐values. We therefore suggest that b‐values could be highly sensitive to temporal stress variations.