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Study on Eruption Process and Seismicity in Southeast Asia

东南亚火山喷发过程与地震活动研究

基本信息

批准号：
06044258
负责人：
IRIKURA Kojiro
金额：
--
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Overseas Scientific Survey.
财政年份：
1994
资助国家：
日本
起止时间：
1994 至无数据
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-06044258/
关键词：
Andesitic Volcano Eruption Mechanism Precursor Volcanic Gases Pyroclastic Flows Volcanic Earthquakes Ground Deformation

项目摘要

Five Indonesian volcanoes which were seismically active or erupted in 1994 were investigated from geophysical and geochemical points of view in cooperation with the Volcanological Survey of Indonesia. The main results are as follows ;1. Precursor of the big pyroclastic flows generated on Nov.22,1994 at Merapi volcano was observed with geochemical and geophysical observation, though seismic precursor was not clearly identified. Chemical composition of volcanic gases were changed about one month before. The emission rate of sulfur dioxide clearly increased and, a tiltmeter indicated inflation of the summit one week before the pyroclastic flows. These results suggest that new magma came up just before the activity, and how important comprehensive observation is for prediction of volcanic activity.2. The waveforms of volcanic earthquakes and tremors observed at Semeru are quite similar with those at Sakurajima. Before the 1994 explosive activity, A-type earthquakes occurred frequently and then B-type earthquakes increased. Finally, swarms of volcanic earthquakes and tremors were observed. Such a seismic sequence before eruptions has been frequently experienced at Sakurajima and Asama Volcanoes. This result suggests that seismic events and volcanic process may be common at andesitic volcanoes which have repeated explosive eruptions.3. Precise hypocentral determination of volcanic earthquakes was done at Guntur volcano. An aseismic zone at deeper part than 5 km beneath the summit was found. This is similar with that at Sakurajima, Merapi and Asama Volcanoes, and suggests the probable location of the magma chamber at the volcano.4.Before eruptions at Batur and Guntur, the Volcanological Survey of Indonesia recognized seismic precursors and succeeded the forecasting eruptions.

与印度尼西亚火山学调查局合作，从地球物理和地球化学的角度调查了1994年地震活跃或爆发的印度尼西亚五座火山。主要研究结果如下：1994年11月22日发生在默拉皮火山的大火山碎屑流，通过地球化学和地球物理观测观测到了其前兆，但地震前兆识别不清楚。火山气体的化学成分大约在一个月前发生了变化。二氧化硫的排放率明显增加，在火山碎屑流开始前一周，一个倾斜计显示峰顶出现了膨胀。这些结果表明，新的岩浆是在活动之前出现的，综合观测对于预测火山活动是多么重要。在塞默鲁观测到的火山地震和震动波形与樱岛观测到的非常相似。1994年爆炸活动前，a型地震频发，之后b型地震增多。最后，观测到了火山地震和震颤群。樱岛火山和浅间火山在爆发前经常经历这样的地震序列。这一结果表明，地震事件和火山作用可能在反复爆发的安山岩火山上是共同的。在Guntur火山进行了火山地震的精确震源测定。在山顶以下5公里处发现了地震带。这与樱岛火山、默拉皮火山和浅间火山的情况相似，表明了火山岩浆库的可能位置。在Batur和Guntur火山喷发前，印度尼西亚火山调查局识别了地震前兆，并成功预测了火山喷发。