Average slip rate at the transition zone on the plate interface beneath the Kii Peninsula, Japan, estimated from deep low-frequency tremors

We investigated the average slip rate at the transition zone on the plate interface beneath the Kii Peninsula, Japan, using an empirical method based on a proportional relation of sizes between short-term slow slip events and nonvolcanic deep low-frequency tremors. The estimated average slip rates are 3.0±0.4 cm/yr, 2.6±0.4 cm/yr, and 2.4±0.4 cm/yr, in the northern, central, and southern Kii Peninsula, respectively. Values in the northern and the central areas compensate for the difference between the slip deficit rate at the transition zone and the convergence rate of the subducting Philippine Sea plate. The discrepancy among those rates is, however, large in the southern area, suggesting a lateral variation in the proportional relation or the existence of a steady, or quasi-steady, slip.