Two‐dimensional model calculations of earthquake cycle on a fluid‐infiltrated plate interface at a subduction zone: Focal depth dependence on pore pressure conditions

Abstract

We execute 2D model calculations of earthquake cycle at a subduction zone to compare two types of pore pressure models on a plate interface: hydrostatic pressure model and excess pressure model. In addition, we discuss the pore pressure fluctuations due to pore dilatation and compaction on the fluid‐infiltrated plate interface. The calculation results suggest: (1) The hydrostatic pressure model tends to produce the deeper hypocenters located around the bottom of the seismogenic zone than the excess pressure model. (2) Pore pressure fluctuations owing to pore dilatation and compaction in the deeper zone than the décollement tend to shallow a focal depth in the excess pressure model. We find that the focal depth and the recurrence interval of interplate earthquakes depend not only on the frictional parameters but also on the pore pressure conditions.