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THE WHOLE HISTORY OF EARTH'S ENVIRONMENTAL CHANGE IS RECORDED ON THE DEEP
SEA BOTTOM
- GEOLOGICAL STUDIES
- Today, it is believed that the earth's surface consists of a number
of plates. When two of such plates meets and one of them subducts
underneath the other, a trench is created. When two plates separates
from one another, a volcanic activity is created to fill the gap, and a
large ridge named the "mid-ocean ridge". Therefore, regions of such
trenches and mid-ocean ridge are geologically active, where seismic
and/or volcanic activities occur frequently. The mid-ocean ridge are
usually located several thousand meters below sea level, and their
actual status is not clearly known. However, new volcanoes and
hydrothermal activities related to volcanism are observed, and this
region is one of the important study themes in earth science.
There exist trenches exceeding 6,000 meters along the Japanese Islands, and it is believed that plates subduct along there trenches. As this subduction causes earthquakes and volcanic activities on the land side, the mechanics of trench is deemed important in analyzing seismo / volcanic phenomena. At the central part of a plate, where there is no interference from other plates, sediments accumulate quietly on the sea bottom some 5000 meter deep, and manganese nodules are frequently produced. JAMSTEC is conducting geological researches by observing the conditions of sea bottom and bottom sediments sampling.
We uses three methods in its plan for long-term observations of the deep-sea floor. They include a self-recording method, real-time method and buoy satellite method, which has provided a great deal of data in 1993. A comprehensive ocean floor observation station was established in September 1993 in a clam bed in water 1,174 m deep off Hatsushima Island in Sagami Bay. Long-term observations were begun using a real-time method.
Click here! This is a 'Window of Deep Sea Floor'.
- RESEARCH OF DEEP SEA CREATURE
- Deep sea surveys conducted during recent years have revealed the
existence of deep sea biological communities, composed of organisms
scarcely known in the past, at deep sea hydrothermal vent and cold seep
areas. It is apparent that such communities or ecosystems which are
sustained by chemical synthesis of microbes that do not depend on solar
energy, but instead utilize the chemical energy of substances supplied
from the deep sea bottom. The studies of there communities are one of
the major focuses of the world attention in deep sea biology. Colonies
of vesicomyid clams, vestimentiferans have been found by the submersible
"Shinkai 2000" and other deep sea survey systems at depths of several
hundred to several thousand meters in Sagami Bay, Okinawa Trough, and
Ogasawara(Bonin) Island area. Basic studies of there communities are
being conducted by JAMSTEC.
- RESEARCH OF DEEP SEA MICROORGANISMS(DEEP STAR)
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Attention has been focused on the unique microorganisms that grow under such special environment of deep sea bottom where hot water ejects or cold water seeps out. Basic researches are being conducted to understand the mechanism by which they can stand high pressure, high temperature or low temperature, and to clarify the biological characteristics such as genes and proteins.
Two support projects, the development of deep sea microorganisms collecting and cultivating system, and the preservation and distribution of deep sea microorganisms, are implemented for effectively making them available the researches. The deep sea microorganisms inhabit is collected and brought to the land by the research submersible, etc., and the isolation and cultivation of microorganisms can be performed under the pressure and temperature conditions similar to the deep sea environment. The system consists of four subsystems, the mud collector, diluting equipment, separating equipment and cultivating bath. With the preservation and distribution deep sea microorganisms, it is intended to systematically classify and preserve the deep sea microorganisms to be obtained through activities of the research group, and to distribute them for the scientific community at large.
Photo Library
Chimney Chimney,,
- DEEP SEA RESEARCH TECHNOLOGY
- RESEARCH ON SUBMARINE TOPOGRAPHY
- It is essential to obtain detailed physiographic information of sea
floor before it is surveyed by submarine vessels efficiently and safely.
In JAMSTEC, the sea floor topography is identified beforehand by ocean
survey vessel "Kaiyo" or support ship "Yokosuka" by means of sonar depth
sounding employing the multiple narrow beams. Together with the high
precision measurement of ship's location, precise preliminary mapping is
developed before the submarine surveying. Also, as such topographic data
contain various information, we are developing an algorithm by which
valuable information can be extracted from the high precision depth
sounding date concerning the history of formation of sea floor, crustal
movement in the past, and the history of large scale crustal movement.
- RESEARCH ON SAMPLING SYSTEM OF SEA BOTTOM DEEP STRATA
- In promoting researches of global scale to clarify the mechanism of
earthquakes and volcanic activities that are caused by subduction of
ocean plates, and to enable prediction of seismo / volcanic activities,
it is required to have the knowledge on the whole history of changes in
earth's environment from past to the present time. As such history is
recorded in the sediments at the sea bottom which has been accumulated
for hundreds of million years, invaluable data leading to the past of
earth can be obtained if such sedimentation can be recovered. For this
purpose, it is required to develop the technology to collect samples
from the deep strata at the sea bottom, or the sea bottom deep strata
sampling system.
- RESEARCH CONDUCTED BY DEEP SEA BOTTOM EXPLORATION SYSTEM
- The manned submersible survey vessel and unmanned exploration system are used in conducting researches in deep sea areas. JAMSTEC has developed the manned submersible survey vessels, "Shinkai 6500" and "Shinkai 2000", the towed deep sea exploration system (Deep Tow), rated 6,000m, and the remote controlled unmanned exploration system, "Dolphin 3K" (ROV), operable at 3300m. In addition, the small diameter cable type remote controlled unmanned explorer rated at maximum operating depth of 2000m, and the 10,000m class remote controlled unmanned survey system are currently under construction. The research and development program, in cooperation with the Woods Hole Oceanographic Institute (WHOI) of U.S.A for an autonomous underwater vehicle (AUV), which needs no cable, is currently in progress.