摘要
2002和2003年夏季流动地震观测揭示,天池火山口附近存在大量的微震活动和一系列震群活动.地震定位结果表明地震主要发生在火山口附近,以震群形式发生的地震全部集中在天池火山口西南部,东北部地震密集区没有观测到震群活动.在夏季以外的其他季节,天池火山区只有一个固定地震台站(CBS)用于地震监测.利用CBS台不同时间的观测纪录,通过波形相关分析发现其他季节的主要震群活动仍然集中在天池西南部.震群的高精度相对定位揭示震源位置沿北西-南东向分布,倾向西南,倾角约80°.2003年7月13日的震群发生期间,地震震源位置出现从深到浅的迁移现象,同时震源深度较大的地震在不同台站的地震波初动方向几乎全部向上,表明震源具有明显的膨胀分量.考虑到长白山天池火山2002年以来出现明显的地表形变、地球化学异常和谐频地震等现象,我们认为震群活动可能与5km深度附近存在岩浆热液活动和岩浆增压有关.
In summers of 2002 and 2003, temporary seismic stations recorded a large number of small earthquakes and a series of swarms near Changbaishan Tianchi volcano. Earthquake location result shows that these earthquakes mainly occurred near the Tianchi caldera. Almost all swarms were concentrated at southwest of the caldera, and no swarms occurred in northeast area where earthquakes densely concentrated. In other seasons, the permanent station CBS is the only seismic station to monitor volcanic earthquakes in Tianchi volcano. Waveform correlation analysis of seismic data recorded at CBS in different time shows that earthquake swarms occurred in other seasons also concentrated in the southwest Tianchi Lake. High-precision relative location shows that hypocenters of earthquake swarm distributed along northwest with a dip angle of 80° to southwest. During the July 13, 2003 earthquake swarm the hypocenters migrated from deep to shallow and deeper events had upward first motion directions at almost all stations. That means they had obvious expansion component in source mechanism. Taking into account of significant surface deformation in Changbaishan Tianchi volcano since 2002, geochemical anomalies and harmonic-spectral earthquakes, we believe that the earthquake swarm activity was caused by magmatic and hydrothermal activity and pressure increase of magma near the depth of 5 km.
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2007年第4期1089-1096,共8页
Chinese Journal of Geophysics
基金
国家科技支撑计划项目(2006BAC01B04)
地震科学联合基金(106023)资助
中国地震局地球物理研究所论著号:07AC1003.
关键词
震群
火山
长白山
Earthquake swarm, Volcano, Changbaishan
作者简介
吴建平，男，1963年生，研究员，主要从事地球内部速度结构和火山地震学研究．E-mail：wjpwu@cea-igp.ac．cn
