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从地势上看,中国西部以巍峨的高山、广阔的高原和盆地著称,东部则以平原和丘陵为主,两者差异显著。地球物理研究已查明,中国东部和西部有截然不同的重力场、相差甚大的地壳厚度。值得注意的是,在中国东西两部分的交界地区,即大约在东经100°—108°的狭长地带,不仅是地球物理场急剧变化的过渡地带,而且也是引人注目的地震带,通常称为南北地震带。据粗略统计,就1960—1969年四级以上的地震而论,南北地震带
From the topography, western China is famous for its majestic mountains, vast plateaus and basins, while the eastern part is dominated by plains and hills, with significant differences between the two. Geophysical research has identified distinctly different gravitational fields in the east and west of China, with widely varying crustal thicknesses. It is noteworthy that at the junction of two parts of China, namely in a strip of land roughly 100 ° -108 ° east longitude, it is not only a rapidly changing transition zone of the geophysical field but also an attractive seismic zone, commonly referred to as North-South seismic belt. According to rough statistics, in terms of earthquakes above the fourth grade from 1960 to 1969, the North-South seismic belt