What controls the occurrence of shallow intraplate earthquakes?

We simulated the occurrence of both intraplate and interplate earthquakes in a simple spring-slider-dashpot model that includes both types of earthquake faults. We found that recurrence intervals of intraplate earthquakes are not controlled by the velocity of the relative plate motion but by the viscosity in the ductile fault zone, the coefficients of friction of both the interplate and intraplate earthquake faults, and the stress drop of intraplate earthquakes, when the stress drop of intraplate earthquakes is assumed to be only a small part of the total shear stress. These findings may open new avenues for the physics-based long-term forecasting of intraplate earthquakes.