祁连山中段深部电性结构及潜在震源危险区的研究
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摘要
位于青藏高原北缘的祁连山中段是地震十分活跃的地区之一。本课题采用ＭＴ重复测量方法，在该区建立的长约４００ｋｍ的剖面上进行监测。本文根据监测所获取的ＭＴ参数，从静态的角度探讨了该区深部电性结构及其电性横向变化特征，进而评估了该区的潜在震源区。研究发现，该区深部介质电性的物质特征有：１．部分地带呈现出剧烈的电性横向变化，２．具有极为发育的特殊增厚的壳内高导层地段，３具有高、低热流的过渡边缘地带，４．具有与活动大断裂相交汇的隐伏断裂构造的局部地段。近年来该区地震活动增强，数次中强地震都发生在具有上述特征的地带中，该地带将可能是祁连山中段的强震－大震潜在震源危险区。这四种电性特征将是潜在震源区的判别标志。
Middle part of Mt. Qilian is one of the seismic active regions at the northern margin of the Qinghai-Tibet plateau. The MT repeated measurement had been adopted to the measurement along a section of 400 km long in this region in the research. The deeper structure of electricity and its horizontal variation were studied statically here by the obtained MT data, furthermove potential seismic risk areas were evaluated. Researches show the following characteristics of electric property of deeper media:1.Intensive horizontal electric property variation appeared in some areas. 2.Special high conductive layer in crust were exist. 3.Edge area were found exist between higher and lower thermal current layers. 4.The intersection of concealing fault tectonics with large scale active fault was revealed. The seismic activity in this region has increased and some moderately strong shocks have occurred in areas of above characteristics in recent years.They show the middle Mt. Qilian migth be the seismic risk area of strong earthquakes, and above mentioned four characteristics of electric property could be taken as criteria of seismic risk area.
Middle part of Mt. Qilian is one of the seismic active regions at the northern margin of the Qinghai-Tibet plateau. The MT repeated measurement had been adopted to the measurement along a section of 400 km long in this region in the research. The deeper structure of electricity and its horizontal variation were studied statically here by the obtained MT data, furthermove potential seismic risk areas were evaluated. Researches show the following characteristics of electric property of deeper media:1.Intensive horizontal electric property variation appeared in some areas. 2.Special high conductive layer in crust were exist. 3.Edge area were found exist between higher and lower thermal current layers. 4.The intersection of concealing fault tectonics with large scale active fault was revealed. The seismic activity in this region has increased and some moderately strong shocks have occurred in areas of above characteristics in recent years.They show the middle Mt. Qilian migth be the seismic risk area of strong earthquakes, and above mentioned four characteristics of electric property could be taken as criteria of seismic risk area.
引文
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