四川盆地潜在震源区的细致划分

Attentive seismic hazard mapping for Sichuan Basin

四川盆地包括川中台拱和川东陷褶束的范围,具有相对稳定的大地构造环境。鉴于该地区地震活动水平相对较低、发震构造不甚明确的特点,在编制1990年版中国地震烈度区划图时,划分的潜在震源区面积也相对较大。本文在总结四川盆地中强地震(Ms=4.7-5.7)发震构造条件的基础上,用地震构造类比原则对四川盆地的潜在震源区进行了重新划分。确定潜在震源区边界时,充分考虑了背斜轴走向、背斜构造的影响带宽度、小震活动密集条带和余震的分布范围。得到了四川盆地更加细致的潜在震源区划分方案。这对于低地震活动水平地区的潜在震源区的细化研究具有一定参考意义。

The extension of Chengdu Basin we discuss in this paper includes the middle and the eastern part of Sichuan Basin and is a stable geotectonic environment. The seismicity level is low but the seismogenic structures are not clear. The geotectonic condition of the medium and strong earthquades magnitude with Ms = 4.7 - 5.7 in Sichuan Basin are summarized. Basing on the summaries above and the comparison rule of seismogenic structure, we re-map the seismic hazard region in Sichuan Basin. We attentively consider the direction of anticline axes , the affect width of anticline structures , the belts of intensive small earthquakes and the distribution of aftershocks to determine the region boundaries of the seismic tendency. This map will be valuable for the detailed researches of seismic tendency.