Spatial distribution of b-values reflects the heterogeneity in both stress distribution and material properties within the seismogenic zone. The pattern of Coulomb stress failure postulates that the NW-SE normal fault zone is of fundamental importance in producing seismicity and magmatic intrusions in the crust under the HL. Crustal heterogeneity under HL acts as an asperity in the epicentral area, whose origin may relate to magma intrusion into upper crust.