VENUS Project: (Fy1995-99)
Versatile Ecomonitoring Network by Undersea-cable System
VENUS "Geomagnetic and Electric Fields Observation System" (VenusOBEM)
is developed by the Geological Survey of Japan (GSJ)
is developed by the Geological Survey of Japan (GSJ)
| The whole project includes following Ocean-Bottom
observations. (1) Hydrophone array, (2) Broadband seismometer, (3) Geomagnetic and electric field observation, (4) Multi-sensor observation (CTD, Video, Thermometer, Current meter, etc.) (5) Acoustic ranger, (6) Acoustically communicating maneuverable observation, (7) Tsunami guage, and (8) Geomagnetic disturbance observation (on land). Among them, GSJ took charge of (3) Geomagnetic and electric field observation.
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| Geomagnetic and Electric Fields
Observation System (by Geological Survey of Japan) |
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Specification | ||
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Dry Dock Test in July, 1999 | |||
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Dock Test sample record in July, 1999 | |||
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Deepsea Landing in Sep., 1999 | |||
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Deployment and Connection in Sep.- Oct., 1999 | |||
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Sample record at the Okinawa Site in October, 1999 | |||
| Abstract of Final Report | report 1
report 2 | |||
| Summary of observation | Records obtained by VenusOBEM (PDF) 42-days observation at the Okinawa deep-sea site (top) and data from Kakioka Magnetic Observatory (middle) are well-correlated, with slight differences due to the difference in latitude. Variations related to a magnetic storm took place on Oct. 22, 1999 (JST), and subsequent electro-magnetic phenomena are shown on the bottom graph. Electric field data are represented as the voltage between two electrodes separated by about 20 meters. The disturbances in the electric field data became much larger after November 06, which might indicate some unknown process related to the progress to the stop of whole observation system. | |||
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The whole system of Ocean-Bottom observation fell down abruptly on Nov.19,
1999. All attempts of restarting operation were not effective, and the
system died on Nov.20. Later inspection of the system revealed some kind of trouble at the power supply unit in the Juncion box, which presumably came from insuration breakdown in some units. | ||||
| Comprehensive Final Report Paper | Kasahara, J., R. Iwase, T. Nakatsuka, Y. Nagaya, Y. Shirasaki, K. Kawaguchi, and J. Kojima (2006) An experimental multidisciplinary observatory (VENUS) at the Ryukyu Trench using the Guam-Okinawa Geophysical Submarine Cable. Annals of Geophysics, 49, 595-606. | |||
