鄂尔多斯地块周缘地震活动周期及迁移特性

PERIODICITY AND MIGRATING CHARACTERISTICS OF SEISMIC ACTIVITY ALONG THE MARGIN OF ORDOS BLOCK

根据中国历史地震资料及现代地震观察资料,研究了鄂尔多斯地块周缘地震活动时间上的周期性及空间上的某些迁移特性。发现:地块周缘的地震活动有700—900年的活跃期;300—400年的活跃幕;20—30年的活跃段。在活跃期中,大震有绕地块周缘逆时针迁移趋势;在活跃幕、段中,中、强震有绕地块周缘顺、逆时针相间转动迁移趋势,并有对角、对边及反向迁移特征。

On the basis of historical earthquakes in China and observational data of recent earthquakes, the temporal periodicity and the spatial migration characteristics of seismic activity along margin of Ordos Block has been studied in this paper. It has been found that there were seismic active period of 700-900 years,seismic active episode of 300-400 years,and a seismic active segment of 20-30 years in seismicity along the margin of Ordos Block. In active period,strong earthquakes have tendency of migrating anticlockwise. In seismic active episode and segment, medium and strong earthquake have tendency of clockwise and anticlockwise alternately migrating along the margin of Ordos Block. In the same time, there were also the characteristics of strong earthquake migrating along direction of opposite angles,opposite sides of Ordos Block and in reversal direction.