Long-Term Deep Sea Floor Observatory off Hatsushima Island in Sagami Bay

The swarm earthquakes and underwater volcanic eruption in the western part of Sagami bay are considered caused by the collision of Philippine plate and North American plate.

Vesicomyd Clams, large size bivalve, which were discovered by a deep sea manned submersible "Shinkai 2000" in 1984 at the sea floor of 1,100 meters off Hatsushima Island are peculiar creature (chemotroph) which live on utilizing methane and sulfide seeping from undersea faults.
As the inhabitation condition of vesicomyd clams has close relation with collision of tectonic plates, longterm observation of seafloor is considered to bring us some data indicating outbreak of natural phenomena such as earthquakes.

JAMSTEC deployed the first real time deep seafloor station and started longterm observation in 1993 at a colony of vesicomyd clams on the seafloor of 1,174 meters in depth. It was replaced by a new station in 2,000.

This observation station is equipped with many kinds of sensors such as television cameras, a seismometer, a pressure gauge and a current-meter. New kind of sensors can also be connected to the station as it is equipped with plural underwater mateable connectors.

The observation data are transmitted to Hatsushima Island in real-time through an optic/electric composite cable of about 9 kilometers in length.
Until now, many phenomena and related informations have been obtained such as spawnings of vesicomyd clams and underwater mud flow due to swarm earthquakes.

Off Hatsushima System


Equipment Note
Observation Station -- Video Camera
-- Seismometer
-- Tsunami Sensor
-- CTD
-- Hydrophone
-- Gamma-ray sensor
Hatsushima Land Station Transmission of observation data to JAMSTEC


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