1989 Fiscal Year Final Research Report Summary
Development of an Ocean Bottom Seismometer to be installed on hard rock by a submarine.
| Project/Area Number |
63460040
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
固体地球物理学
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
ANDO Masataka Kyoto Univ.DPRI.Associate Prof., 防災研究所, 助教授 (80027292)
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| Co-Investigator(Kenkyū-buntansha) |
IRIKURA Kojiro Kyoto Univ.DPRI.Prof., 防災研究所, 教授 (10027253)
OIKE Kazuo Kyoto Univ.Faculty of Science Prof., 理学部, 教授 (40027248)
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| Project Period (FY) |
1988 – 1989
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| Keywords | Seismic observation at ocean bottom / digital ocean-bottom seismograph / submarine ship / submarine geophysics / Interior of the Earth / seismic swarm / seismic doservation |
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| Research Abstract |
A digital ocean-bottom seismograph has been developed, which was designed to be installed on ocean-bottom hard rock by using the submarine research ship "SHINKAI 2000".
The sensor consists of 1 vertical and 2 horizontal components with a natural pendulum period of 1 second. Ground motions are recorded on PROM memory when their amplitudes exceed over a pre-set level. A triggered event is recorded for a period of 250 second and thus the total of 51 events can be stored on the PROM memory of 4 mega bytes with 12 bits of resolution and at a rate of 50 samples per second.
The sensor, amplifier, memories and so on are all put in a 17" glass pressure-vessel. The glass sphere, covered with a hard plastic container, transponder, weight and others are all assembled with a hard leg-frame. All parameters such as starting time of measurement, trigger component (s) , triggering level, and so on are set with commands by an external portable type computer before closing the vessel.
The OBS was set in the Okinawa trough for 5 days in September 1988, and recorded 11 seismic events and back-ground noises during the observations.
After this observation, some modification were made for this OBS.The aluminium, anti-pressure vessel was used instead of the glass vessel. The amount of memory was increased. And software for triggering was improved.
Using a new OBS off the east coast of Ito, Central Japan, where seismic swarm and a submarine eruption occurred in 1989, seismic observation was made before this swarm.
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