长白山天池火山地震类型及火山活动性的初步研究

2002年以来，长白山天池火山区出现了地震活动增强、地形变加剧和多种地球化学异常等现象，火山口附近发生的多次有感地震在社会上产生了较大影响。本文利用2002年以来的流动地震观测资料，采用频谱分析、时频分析和多台站资料对比的方法，对火山区地震事件的类型进行了分析；对火山活动的危险性进行了初步研究。结果表明，目前天池火山区出现的大量地震活动仍然属于火山构造地震，少量台站地震记录中表现出的低频特征主要是由于局部介质影响造成的，排除了长周期地震引起的可能。尽管长白山天池火山地震活动明最增强，震群活动较为频繁，但仍属于岩浆活动的早期阶段，短期内发生火山喷发的危险性较小。

A Preliminary Study of Types of Volcanic Earthquakes and Volcanic Activity in Changbaishan, Tianchi Volcano

A significant increase in seismicity, obvious ground deformation and geochemical anomalies have been observed in Changbaishan, Tianchi volcanic area since 2002. A series felt earthquakes occurred near in the caldera caused great influence on society. The types of volcanic earthquakes recorded by temporal seismic network since 2002 have been classified by analyzing of the spectrum, time-frequency characteristics and seismic waveforms at different stations. The risk of volcano eruption was also estimated. The result shows that almost all earthquakes occurred in the Tianchi volcano are volcanic-tectonic earthquakes at present. The low frequency seismic waveforms observed at a few stations might be caused by local medium, and have no relation with Long-Period events. Although the level of seismicity increased obviously and earthquake swarms occurred more frequently than before, we considered that the magma activity is still in its early stage and the eruption risk of Changbaishan, Tianchi volcano is still low in near future.