摘要
利用 1984～ 1998年间期间发生在腾冲火山及邻区 30个台站记录的数千个地震的P波资料 ,采用地震层析成象法重建了腾冲火山及邻区地壳、上地幔不同深度的三维速度结构层析成象图。结果给出 ,在腾冲火山区下面地壳内约 3～ 9km存在低速带 ,扰动量达 - 10 % ;10～ 15km深度为高波速带 ,扰动量达 7 3% ;16～2 4km深度为低波速带。扰动量达 - 9 1% ;2 5～ 40km为高波速带 ,扰动量达 10 % ;大于莫霍面深度 (h≥42km)以下均为低波速带。本文所得的腾冲火山区地壳分层速度结构层析成象图是迄今为止最为详细的成象研究成果 ,其中一个重要结果是发现在火山区下不同深度存在两个高波速带 ,不是象以往报道的整个火山区下为低波速带。根据本文成析成象结果 ,结合数字化近场地震观测资料及震源力学参数特征解释 ,分析认为 ,腾冲火山区地壳不同深度存在的低速带或高速带均与火山作用的岩浆活动有密切关系。低速带可解释为与岩浆囊或半熔融热物质有关 ,高速带可解释为与地壳岩浆通道内剩留岩浆逐渐冷却固化组成的超铁镁堆积岩形成的火山核有关。本文所得的三维速度层析成象结果 ,可为研究腾冲火山喷发机理、岩浆运移系统动力成因以及火山喷发预测与预防等方面深入研究提供重要参考。
D pattern of velocity structure in crust and upper mantle at different depths in Tengchong volcano areas and nearby has been reconstructed by chromatography that from data of several thousand earthquakes recorded at 30 stations, which happened in 1984-1998. The results show that there exists a low velocity belt at 3-9km with -10% disturbance, a high velocity belt at 10-15km with 7 3% disturbance, a low velocity belt at 16-24km with -9 1%, and a high velocity belt at 25-40km with 10% disturbance. All depths greater than Moho(h≥42km) are low velocity belts. The pattern of velocity structure obtained by chromatography is a most detailed result up to now. Instead of low velocity belts in whole volcano areas reported in the past, one of the results is that there exist two high velocity belts at different depths. Considering near field observation and parameter interpretation of source mechanics, the authors think that the low or higt velocity belts in Tengchong volcano areas are closely related to the magma activities of the volcanoes. The low velocity belt can be interpreted as having relation with magma pocket or half melting hot substances. And the high velocity belt can be interpreted that it is related to volcanic core that formed by superferro-magnesium. The 3-D pattern is a good reference to study mechanism of volcano eruption, magma movement and prediction and preparedness of volcano.
出处
《地震研究》
CSCD
北大核心
2000年第2期157-164,共8页
Journal of Seismological Research
基金
国家自然科学基金!(D0 40 7)
地震科学联合基金!( 199119)资助项目
云南省科技攻关项目
关键词
层析成象
速度结构
腾冲火山区
地震资料
chromatography, velocity structure, transversal inhomogeneity, Tengchong volcano
