腾冲火山地区的地震活动特征

The seismicity feature of the volcanic area in Tengchong

对腾冲火山地区的地震活动时空分布及震情参数的研究结果表明，与火山活动区有关的地震活动具有以下特征：周围构造地震活动频繁而火山群地区则处于地震活动相对平静的背景，震级较低（最高为５．０～６．０级）；地震活动以小的震群活动为主，微震主要发生在腾冲县城南部的热海热田地区。长期的地震频率ｂ值高，达１．２左右；震源深度在０～２０ｋｍ范围，受周围构造大地震的影响，导致火山区地壳内部岩浆活动引起的岩浆冲击型地震发生；火山体地下低速层的存在与地下热物质有关。从腾冲火山活动区地震的时空分布特征和震情参数特征表现出与世界上其它火山地震的相似关系，表明腾冲火山不是死火山，火山体地壳内部存在的岩浆囊或岩浆移动通道内岩浆仍在活动。

The temporal and spatial feature and seismologic parameters of the seismicity from volcanic activity area in Tengchong are studied in this paper. Results of the study show that the seismic frequency and intensity is low in volcanic area, the sreatest masnitudes 5. 0 to 6. 0, while the seismic frequency is high around the Tengchong volcano area, and micro-earthquake sequences activity is the dominant fsctor for seismic events occurred in volcanic area, most ofthe microseismicity occurred in southern Tengchong, and a long-term seismic frequence b value is high (up to 1.2), and the focal depth is between 0～20 km, the magma-impact type earthquakes are outcome of the tectonic seismicity, and the low velocity layer existence beneath volcanic bodies is proved to be related with the hot materials in earth deep. Restults of the study for the temporal and spatial distribution feature and seismologic parameters of the earthquakes in Tengchong area are in accord with the results given by different volcano areas in world. This shows that Tenschong volcano is not extinct volcano, the magma bodies still moves in the volcano's interior.