青海省门源地震构造背景遥感分析

THE ANALYSIS OF THE STRUCTURE BACKGROUND FOR MENYUAN EARTHQUAKE WITH REMOTE SENSING METHOD IN QINGHAI PROVINCE

位于祁连山北麓的青海省门源地区干１９８６年８—９月先后发生了三次地震，最强的一次震级 为６．４级。在调查地震发生的地质背景和地震破坏情况中，遥感技术发挥了重要作用．通过对卫星 图像和地震前、后摄制的航空像片解译，发现门源地震正位于祁连山与河西走廊的交接带上，区 内断裂构造十分发育，主要展布方向为北西向，它们控制着山间盆地和谷地的形成，而且．在新构 造运动时期具有较强的活动性，如第四纪地层被断；地貌差异显著；水系和山脊位错变形；洪积 扇出现叠置和偏移；地震鼓包和地裂缝等迹象在遥感影像上都有较清楚的显示，结合地质、地震 资料分析，区内新构造运动强烈，特别是祁连山北缘断裂活动更为明显。在这一活动带上，历史 上曾发生过海原、古浪、昌马等大地震，小震更是时有发生。所以，我们认为北西向的祁连山北 缘断裂是一条孕震断裂，门源地震与其有密切关系，并且该断裂的中东段今后仍会有中强地震 发生。

The Menyuan area of the Qinghai Province lies to the northern foot of the Qilian Mountain, three times of earthquake took place from August through September of 1986, the strongest of which is magnitude 6.4 (on the Richter scale). Remote sensing technology played an important role in the investigation of geological background and damage caused by earthquake. By the interpretation of satellite images and aerophotos produced before and after the earthquake, it is found that Menyuan earthquake is on the connected zone between Qilian Mountain and the Hexi Corridor. The well-developed fault structures, distributed mainly in the northwest direction, control the formation of intermontane basins and valley basins, and are very active in the period of new structure movement, such as the Quaternary strata are fractured; the geomorphological difference is clear; the drainage system and ridges are deformed; the proluvial fans are folded and displaced. Remote sensing images show the earthquake bulges and earth crevices clearly. Analysing these images and combining with geological and earthquake information, it is found that a new structure activity is strong in this area, especially the fault activities at the northern foot of Qilian Mountain. Some major earthquakes such as Haiyuan, Gulang and Changna took place in the past on this active zone, and there were more minor earthquakes also It is Considered that the northwest fault at the northern foot of Qilian Mountain is an earthquake source and has close relation with Menyuan earthquake. On the middle and east part of this fault, some strong and moderate earthquake will take place in the future.