Short-term slow slip and correlated tremor episodes in the Tokai region, central Japan

We observe the related phenomenon of short-term slow slip event (SSE) and low-frequency nonvolcanic tremor on the deeper extension of the 1944 Tonankai and the anticipated Tokai earthquake rupture areas, central Japan. Japan nation-wide seismometer and tiltmeter array, NIED Hi-net has recorded these correlated episodes of SSE and tremor, known as episodic tremor and slip (ETS) in 2004 and 2005. The events are located on two areas in the Tokai region, one is near the Shima peninsula, and the other is around the Aichi area. Both episodes have a typical duration of 2-3 days and released seismic moment corresponding to M(w) similar to 6.0. Moreover, these episodes repeatedly occur with a recurrence interval of about six months in both areas. This evidence suggests that the coincidence between the SSE and the tremor is a characteristic behavior in the whole tremor belt-like zone in the Nankai trough subduction zone.