Source mechanism of volcanic tremor revealed by waveform analyzes and fluid-dynamic experiments

波形分析和流体动力学实验揭示火山震源机制

• 批准号: 07640547
• 负责人: IDA Yoshiaki
• 金额: $ 1.47万
• 依托单位: University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07640547/
• 关键词: Volcanic earthquake; Volcanic tremor; Asama volcano; A-type earthquake; B-type earthquake; N-type earthquake; 震源分布; 浅間山; 低周波地震; 草津白根山; 発生機構; スペクトル; 微動発生機構

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.

1996年10月在离浅间火山山顶火山口很近的地方新设的4个监测站连续观测，获得了较好的火山地震和震颤波形资料。将这些数据与山顶周围较远的旧台站的数据相结合，火山地震和震颤的性质就得到了更好的理解，如下所述。峰顶火山口下方的火山地震（b型地震）和震颤（低频或n型事件）的震源比之前认为的要浅得多，也更集中在一个狭窄的区域。西侧以下的其他地震（a型地震）往往与这些浅层事件分布在同一条线上，两者之间存在一定的地震间隙。在旧台站的波形中，陨石坑以下浅b型事件的s波相位相当模糊，但在陨石坑附近新台站的波形中，s波相位识别得更清楚。震颤（低频或n型事件）的波形在***处有一个急剧上升，可用来将部分兴奋与部分共振分开。

项目成果

辻浩: "浅間火山の山頂地震観測" 技術研究報告(東京大学地震研究所). NO.2. 135-140 (1997)

辻宏：《浅间火山山顶地震观测》技术研究报告（东京大学地震研究所）NO.2（1997）。

藤田英輔,井田喜明,及川純: "Ergen oscillation of a fluid sphere and source mechanism of monochromatic volcanic tremor" J.Volcanol.Geothem.Res.(印刷中).

Eisuke Fujita、Yoshiaki Ida、Jun Oikawa：“流体球的 Ergen 振荡和单色火山震源机制”J. Geothem Res。

Hiroshi Tsuji: "Seismic observation around the summit area of Asama volcano" Technical Research Report. NO.2. 135-140 (1997)

Hiroshi Tsuji：“浅间火山山顶地区周围的地震观测”技术研究报告。