sagami

At depths of 1,174 meters, approximately 6 km southeast of the "Real-Time Deep Sea Floor Observatory" off shore Hatsushima in Sagami Bay, we find a giant chemosynthetic community composed mainly of Calyptogena (giant white clams). This community thrives on methane and sulfides found in water seeping from underground.

In this sea area, swarm earthquakes activity east off Izu peninsula occurs almost yearly. The region is also a tectonically active region, as demonstrated by the 1989 eruption of Teishi seamount. We will perform real-time observations from several aspects on changes in the deep-sea environment brought about by biological activity and swarm earthquakes.


Exterior view of the station	Turbidity observed at this station in early spring (May 18, 1996, 12:00)	A mudflow accompanying a submarine landslide during an swarm earthquakes, captured by our observation system (March 4, 1997, 13:00).

This station consists of a CTD sensor, electromagnetic current meter, two video cameras, two ground thermometers, a seismograph, and hydrophones. It is linked to the on-land station at Hatsushima by a fiberoptic electromechanical cable of about 8 km.Up to now, we have observed seasonal variations in the amount of suspended particles, which show significant increase in early spring, when Calyptogena spawning occurs. During the swarm earthquakes in March 1997, we were able to videotape the mudflow believed to have occurred following a submarine landslide on the western slope of the station. We recorded changes in ground temperature accompanying this event.

Sagami Bay at a depth of 1,200 meters, this week