关键词: 镜泊湖火山, 地震类型, 地震活动, 地震定位

Abstract: The Jingpohu volcano cluster lies on the southwest of Ningan county seat,Mudanjiang city,Heilongjiang Province,China.There are 13 craters in this area and the volcano cluster formed in Holocene Epoch is concentrated in the two areas of Crater Forest and Hamatang.According to the recent studies,Jingpohu volcano cluster is located on the western side of the Dunhua-Mishan Fault,where the volcanic activity has been highly frequent and the volcanoes were active in Paleocene,Eocene and Holocene.These volcanisms were associated with strong earthquakes of magnitude 6～7.In order to understand the volcanic activities as well as the structure features of crust and upper mantle in this area,14 broadband seismic stations with 24 bit digital seismographs were installed around Crater Forest in Jingpohu volcano area and various seismic events including the volcanic tectonic earthquakes and the volcanic-like events were recorded.In this paper,based on the analysis of a great deal of data,the earthquake type classification,seismicity analysis and earthquake location were carried out.The classification of recorded event types indicate that the earthquakes observed in Jingpohu volcanic area are mainly of volcanic tectonic ones while the seismicity was not high during the recording periods,and at the same time,two types of earthquakes which are different from tectonic ones were recorded.Among these events,the waveform features of one type of events are similar to the volcanic events with long period(LP),however,compared with standard volcanic events with long period(LP),their frequencies are higher;the other type of events have some similar features with volcanic tremors.It could be seen from earthquake location results that the most focus depths range from 10 to 30km and their epicenters are mainly concentrated on the southwestern side of craters.There are few earthquakes in the interior of craters and their magnitudes are mostly less than 2.0.It is suggested that the occurrence of these earthquakes is possibly related with the activities of Dunhua-Mishan fault because the volcanic and seismic activities during observation periods in Jingpohu volcano area are not too obvious and the epicenters are mainly distributed near Crater Forest and Dunhua-Mishan fault.Close attention should be paid to the volcanic-like events with long period and the tremors recorded around Crater Forest.However,it needs further research to make sure that whether the two types of events recorded in this area are related to the magmatic activities because of shorter observation time and a few recorded events available in this study.

Key words: Jingpohu volcano, earthquake type, seismicity, earthquake location