An overview on shallow strong earthquake activity and earthquake live losses of Chinese mainland in the centenary from 1901 to 2001

摘要

This paper reviews and analyses briefly the general characteristics of shallow strong earthquakes (Ms≥6.0, focal depth h≤70 km) in space, time and magnitude and earthquake fatalities of Chinese mainland in the centenary from 1901 to 2001. During the period from 1901 to 2001, there occurred about 420 strong shallow earthquakes with magnitude Ms≥6.0, 88% of them occurred in the western part of the Chinese mainland, which might be related to the strong deformation and motion of the active blocks in the western part. The average focal depth (25 km) in the western part is deeper than that (16 km) in the eastern part, which might be related to obviously thicker crust in the western part. The inhomogeneous distribution of focal depths with the depth profile is related to the variation of frictional and rheologic characteristics with depth in the crust. The shallow strong earthquake activity of Chinese mainland shows a tempo-spatial clustering process. The relation between earthquake magnitude Ms and cumulative frequency Nc is lgNc=8.64-0.99Ms. About 600 000 people died in the earthquakes of Chinese mainland from 1901 to 2001, the most serious earthquake live losses occurred in Hebei Province (250 723 people died) and Ningxia Hui Autonomous Region (246 269 died). There is no a statistically linear relationship between earthquake live losses and magnitudes. The statistical relationship between the earthquake deaths D and cumulative frequency Nc is lgNc=2.40-0.391gD, which shows a fractal distribution.