1991 Fiscal Year Final Research Report Summary
Study on Rupture Initiation by Broadband Records for Local Earthquakes.
| Project/Area Number |
02640310
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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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 | Yokohama City University |
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Principal Investigator |
KIKUCHI Masayuki Yokohama City University Professor, Faculty of Liberal Art and Science, 文理学部, 教授 (20046147)
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| Co-Investigator(Kenkyū-buntansha) |
ISHIDA Mizuho National Research Institute for Earth and Disaster Prevention, Head, Earth Scien, 地圏地球研究部, 研究室長
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| Project Period (FY) |
1990 – 1991
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| Keywords | Broadband Record / Inversion / Rupture Process / Stress drop |
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| Research Abstract |
Body wave data recorded at a network of broadband seismograph stations were analysed to investigate local events with focal depths deeper than about 50 km. For these events the initial portion of P wave displacement represents well the source time function, but only if the amplitude is normalized to the maximum moment rate. The magnitudes of the analysed earthquakes range from Mw=3.1 to 6.5. It is shown than the seismic moment Mo and the pulse width T are well correlated as Mo/T^3=const., indicating that the stress drop is largely constant. This dynamic similarity seems to be valid for a vast range of earthquake sizes : Mw=1-8. Closer inspection of Mo/T^3 indicates that the stress drop slightly depends on the source depth while it is almost independent of whether the source is an inter-plate event or an intra-plate event. It is also shown that source complexity such as a multiple shock nature is not a characteristic of large earthquakes but is often observed even for small earthquakes.
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