1997 Fiscal Year Final Research Report Summary
Source mechanism of volcanic tremor revealed by waveform analyzes and fluid-dynamic experiments
| Project/Area Number |
07640547
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
固体地球物理学
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| Research Institution | University of Tokyo |
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Principal Investigator |
IDA Yoshiaki University of Tokyo Earthquake Research Institute Prefessor, 地震研究所, 教授 (30013535)
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| Co-Investigator(Kenkyū-buntansha) |
OIKAWA Jun University of Tokyo Earthquake Research Institute Research Associate, 地震研究所, 助手 (40262084)
YAMAOKA Koshun Nagoya University School of Science Associate Professor, 理学部, 助教授 (70183118)
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| Project Period (FY) |
1995 – 1996
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| Keywords | Volcanic earthquake / Volcanic tremor / Asama volcano / A-type earthquake / B-type earthquake / N-type earthquake / 震源分布 |
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| Research Abstract |
Good waveform data of volcanic earthquakes and tremor have been obtained from continuous observations at four stations that were newly installed very close to the summit crater of Asama volcano in October, 1996. Adding the data to those from the older stations surrounding the summit in greater distances, the natures of volcanic earthquakes and tremor have been understood much better, as are summarized below.
Hypocenters of the volcanic earthquakes (B-type earthquakes) and tremor (low frequency or N-type event) just bellow the summit crater have turned out to be much shallower and more concentrated into a narrow region than believed previously. Other earthquakes below the west flank (A-type earthauake) tend to be distributed on the same line as these shallow events with some seismic gap between the two groups.
The S-wave phases of the shallow B-type events below the crater were quite ambiguous in the waveforms from the older stations, but they are identified more clearly in those obtained from the new stations near the crater. The waveform of the tremor (low frequency or N-type event) has a sharp rise at the ***set and it is usable to separate part of the excitiaion from the part of resonance.
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