Seismic activity at submarine volcano - OBSH Observations at Suiyo Seamount of Izu-Bonin Arc

We observed seismic signals at Suiyo submarine volcano by small array of 4 Ocean Bottom Seismometers and hydrophones. We deployed 4 OBSH at crater basin near high temperature hydrothermal area from October 4 to October 19. Size of array is several ten meters. Water depth is about 1350 meters. 3 OBSHs have PMD seismic sensors for low frequency wave observation. Local tectonic events and long-period events are popular at all OBSH. Local events, especially long-period events show swarm like activity and it is calm down during low frequency tremor occurred. Many local tectonic events have 1 to 2 second s-p times. They locate near crater rim. Many local events, long-period events and tremor observed only 1 or 2 OBSH. It suggests very shallow activity less than several ten meters scale. It looks shallow active area extend around surface hydrothermal area because no trend in number of local event. It looks no relation of microseismic activity and Long-period events. It looks no clear relation of long-period events, tremor and tide.