Tectonic loading processes affected by volcanoes for the 2008 Iwate–Miyagi intraplate earthquake in northeastern Japan

Abstract

The 2008 Iwate–Miyagi intraplate earthquake (M7.2) occurred close to volcanoes such as Mt. Kurikoma along the southern foothills of the Ou Backbone Range (OBR), northeastern Japan. To understand the generation processes of this intraplate earthquake, 3D modeling of the faulting and tectonic loading processes around the OBR is performed using a finite element analysis considering viscoelasticity and plasticity in a compressional tectonic setting based on our previous 2D modeling. A small high-temperature area is set below the OBR, along with local high-temperature areas caused by volcanoes. In the non-volcanic area between the volcanic regions, two fault zones are generated some distance from the center of the OBR. However, near the volcanic regions, two fault zones are generated close to the center of the OBR. The fault zones corresponding to the Iwate–Miyagi intraplate earthquake are modeled to develop near the volcanic region, which is consistent with observations. The 3D geometry of fault zones and the stress loading processes for this intraplate earthquake were affected by the thermal structure caused by volcanic activity in the region.