关键词: 全球性地震活动高潮, 地震危险性, 青藏高原

Abstract:

This paper studies the temporal and spatial distribution of global great earthquakes(M_W≥8.0)since 1900.We compare two periods of upsurges of great earthquakes occurring in the middle of last century and beginning of this century. The former took place between 1950 and 1965 when 13 great earthquakes(M_W≥8.0)occurred,including 3 events with moment magnitude greater than 9.0.The maximum magnitude in this period reached 9.6.The later period starts since the beginning of this century. In less than 12 years,15 great earthquakes have attacked the world with the largest magnitude of M_W 9.1.On the basis of comparison of these two upsurges of global earthquake activities,we postulate that the ongoing high level of earthquake activity may continue for another 5 years or so. Numerous great earthquakes(M_W≥8.0)and many large earthquakes(M_W 6～7)will occur globally in this 5 years. In addition,this paper also discusses the relationships between earthquake activities along the Sumatra segment of the Indian-Australia plate boundary and that in the Bayankala block in the middle of the Tibetan plateau as well as the plateau itself. The results indicate that Tibetan plateau,especially its middle and southern parts are the likely places for future earthquakes of magnitude over 7.

Key words: global seismicity, upsurge, seismic risk