Group III < System development >
To further improve the observational network, this group is developing new instrumentation and technology as follows.
( 1 ) A high performance ocean bottom seismometer system
This system will enable us to make long term ( typically for
several years ) broad-band seismic observations on the seafloor. This
system is based on the most advanced OBS technology used in temporal
array studies. The sensor will be installed in the ODP hole if
possible. The technical problems to be solved are the requirements for
memory, power supply, data transfer, and overcoming the long period
noise expected on the seafloor.
( 2 ) Ocean bottom geomagnetic observatory
A performance comparable to standard geomagnetic observatories is
required of this system. This system will be installed in the
northwest Pacific.
( 3 ) A high performance magnetometer system for Pacific islands
This is a highly automated system designed especially for the
observations on Pacific islands carried out by Group I. The system
consists of scalar proton and vector fluxgate magnetometers, a
recording unit, a power supply unit, and a GPS synchronized clock.
( 4 ) Observations by use of submarine cables
Submarine cables in the Pacific, retired from telecommunications
service, are being utilized for measurement of electric field
variations on a global scale to study the distribution of electrical
conductivity in the mantle and the dynamics of the core. In the
future, seafloor sensors may be connected to one of such submarine
cables to obtain power and to transmit data.
( 5 ) Ocean bottom geodesy and geothermometry
Monitoring systems for seafloor geodetic and crustal heat flow
measurements will be developed. In the geodetic study, vertical
crustal movement will be monitored by simultaneous measurement of
pressure and gravity on the seafloor.
( 6 ) Superconducting gravimetry
Two superconducting gravimeters will be installed in Australia and
Indonesia. By combing the new data with data from pre-existing sites,
more detailed information is expected to be obtained on the Earth's
deformation, the Earth's rotation, the Earth's free oscillation, and
core dynamics.
( 7 ) Acoustic communication from ocean bottom to surface
Development of this and other technologies including long-life
batteries and satellite telecommunications from sea surface is
essential to realize the potential of the above new observation
systems.
( Y. Hamano )
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