【摘要】 <正> 1974年5月11日3时25分,东经104度,北纬28.2度我国云南省昭通境内发生M=7.1地震。宏观震中为大关县以北,木杆公社钟(杜)家坪附近。震中烈度为IX度。震区为拔海2000米的滇东北高原地区,地面经受强烈切刻,山高坡陡,尤其震区西部,地形尤显陡峻。地形的坡度一般均在30°以上,主要河流的坡降平均为2.53%。该区地质情况比较复杂。地层分布主要为二迭纪阳新统灰岩,峨眉山玄武岩,三迭纪飞仙关砂页岩等等。西部地区还出露部分震旦纪、寒武纪白云质灰岩,奥陶纪石灰岩,极少部分的志留纪更多还原

【Abstract】 From the ground failures caused by Zhao Tong earthquake (11, V, 1974, M = 7.1) in high mountain region may be distinguished many types: the main-the landslides and rock-falls in a wide area, the secondary-the debris flow, dumping, ground crack, ground collaps, the local subsidence in limestone area and so on. It is stressed that the degree of earthquake damage for the high mountain region depends on the stepness of surface slope. The remarkable fact is that the western part of Zhao Tong seismic region suffered to more serious ground failure is a deeply incised area with a steep surface slope (mostly slope > 30? and a greater gradient of river. And the eastern part, in spite of its position near by the epicentral area, has undergone the slighter ground failure due to the different geologic structures and petrologic characteristics as well as the even surface slope.After a stronger earthquake in the high mountain region exists chance of sudden fail triggered by some small earthquakes or other factors, as the broad landslides in Lao-zhai-bao.By comparing the earthquakes damage occurred in mountain regions of western China it is preliminarily recognized that the ground failure caused by earthquakes can be divided into two types, i.e. the seismo-tectonic failure and the seismo-gravita-tional failure. Therefore, the Zhao Tong earthquake damage should be belonging to the latter on account of its failure nature. The bad local topographic and geologic conditions must be taken into consideration in estimation of the Intensity of earthquakes for a certain region.更多还原