Abstract
National Research Institute for Earth Science and Disaster Prevention (NIED) has constructed the nation-wide high-sensitivity seismograph network (Hi-net) equipped with high-sensitivity accelerometer which is available to measure the ground tilt. Here we simply call the high-sensitivity accelerometer, Hi-net Tiltmeter. One of the most important results of the Hi-net Tilt is to discover the short-term slow slip accompanying the non-volcanic tremor. The time duration of less than one week of the short-term slow slip are much shorter than that of the long-term slow slip event which occurred at the Tokai area from 2000 to 2005. The shortterm slow slip recurs with the time interval of six months at some active tremor segments in southwest Japan. The source of the short-term slow slip is rather deeper than that of the longterm slow slip on the plate interface and coincident with the source area of tremor . The shortterm slow slip is a stick-slip as a stress-strain relaxation process at the transition zone on the plate interface.
