1997 Fiscal Year Final Research Report Summary
Study on Lembang and Cimandiri Faults in West Java
| Project/Area Number |
08044077
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Field |
固体地球物理学
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| Research Institution | KYOTO UNIVESITY |
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Principal Investigator |
TANAKA Torao Kyoto University, DPRI,Professor, 防災研究所, 教授 (40027222)
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| Co-Investigator(Kenkyū-buntansha) |
SUPARKA S Academy of Science of Indonesia, Vice-Chairman, 副会長
KAHAR Joenil ITB,Department of Geod.Engineering, Professor, 測地工学科, 教授
NAKAURA Kajuro Kyoto University, DPRI,Research Associate, 防災研究所, 助手 (20135510)
OKUBO Shuhei University, of Tokyo, ERI,Professor, 地震研究所, 教授 (30152078)
ANDO Masataka Kyoto University, DPRI,Professor, 地震研究所, 教授 (80027292)
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| Project Period (FY) |
1996 – 1997
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| Keywords | active volcano / GPS / fault / leveling survey / gravity measurement / seismographic obsevation / IGSN1971 |
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| Research Abstract |
Gravity survey was carried out crossing the Lembang and Cimandiri Faults. Gravity measurements were made with 500n intervals, and GPS observations were also made for precise positioning. A preliminary analysis shows that there is a density contrast between both sides of the faults and that the existence of a layer which tilts to north is expected.
A Reconnaissance seismic observation near the Lembang fault was carried out for about 10 days in October 1997. Two seismographs were set near the Lembang fault. The seismograph consists of three component seismometers with a natural frequency of 2Hz, a digital recorder and a GPS receiver for timing. The recorder has an amplifier, a 16 bit AD-converter and DAT recording system. Some small earthquakes were observed during the observation period. According to reports of the volcanic activity, seismic swarms sometimes occur near active volcanoes. Therefore, seismic activity for small earthquake is not so low near the volcanoes, but not so high near the Lembang fault.
GPS network extended in 1996 was repeatedly observed with Ashtech Z12 and Leica System 300 receivers. The network consists of 7 stations. The size of the network is about 10km and the prcision of positioning is a few mm in rms in average. From repeated GPS measurements a deformation which seems to indicate the buldge of the body of Guntur volcano was detected. Though the deformation is small compared with the positioning precision, it is in agreement with the result from leveling survey at the southeastern foot of the volcaco.
In December 1997 an international symposium was held in Kyoto and investigators of this project participated in the symposium and special meeting in order to discuss the results of this program about the tectonics and structure of Lembang and Cimandiri faults.
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