Interplate quasi-static slip off Sanriku, NE Japan, estimated from repeating earthquakes

Space-time distribution of quasi-static slip on the plate boundary off Sanriku, northeastern (NE) Japan, was estimated by using small repeating earthquakes. We found 2509 repeating earthquakes occurring on the plate boundary for the last 17 years. Based on the interpretation that these events are caused by repeating slips of small asperities surrounded by stable sliding area, we regarded these repeating events as creepmeters embedded on the plate boundary. The results show that deeper portions of the plate boundary are sliding almost stably and earthquakes with magnitudes more than 6 are accompanied by quasi-static slips in the surrounding areas.