中国8级巨震时空特征及其对于大华北地区地震活动影响初析

PRELIMINARY ANALYSIS ON TEMPORAL-SPATIAL DISTRIBUTION CHARACTERISTICS OF M≥8GREAT EARTHQUAKES IN CHINA AND THEIR EFFECTS TO SEISMICITY IN NORTHERN CHINA

中国的8级巨震基本分布在青藏高原南部至云南的弧形带、新疆西北部的北东向条带、35°N一线和南北带、华北强震区、台湾地震区5个区、带,并常常表现出成对性或优势周期.各区、带的巨震活动可能存在不同的主体力源.在新疆和台湾地区发生8级地震后3～10年华北地区北部可能进入6.5级地震密集的地震活跃时段;7～15年后,江淮地震区就可能进入以6级地震为标志的地震活跃时段.华北地区8级地震对大华北二个分区的地震活动都有显著的减震作用.

Great earthquakes M≥8 in China are basically distributed in 5 seismic zones and bands:southern QinghaiTibet Pleateau and Yunnan seismic arc zone,NE striking seismic band in northeastern Xinjiang area,35°N line and SouthNorth seismic band,Northern China strong seismic zone, and Taiwan seismic zone. Very often,the great earthquakes occur in pairs,or with predominant period. Different dynamical sources may exist for the great earthquakes in different seismic zones and bands.3～10 years after the occurrence of an M≥8 earthquake in Xinjiang area or Taiwan Region, a dense seismic activity with magnitude 6.5 may appear in north part of Northern China area, and 7～15 years after the event,Jianghuai seismic zone may enter a seismic active period with the magnitude 6 earthquake as the mark.The great M≥8 earthquakes in Northern China have obvious seismicity reducting effect on the two subzones of Northern China zone.