SEGJ Technical Conference

Resistiviity and Densiy Structute of the intraplate seismogenic zone in hokkaido

Abstract Three-dimensional structural heterogeneity is discussed around two intra-plate earthquake zones in Hokkaido, Japan: Teshikaga area in eastern Hokkaido where several large earthquakes were occurred between 1959 and 1967, and the source area of 2004 Rumoi-nanbu earthquake (M 6.1). Crustal structures of these areas were imaged on the basis of 3-D resistivity model, gravity anomaly and geologic information including borehole data. The obtained models show existence of resistive and high density zones corresponding to rigid geologic bodies in these seismogenic zones. Three dimensional shape of the rigid bodies indicates that strain may be accumulate locally within regional strain concentration zone and cause the intra-plate earthquakes.