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本文对鄂尔多斯块体进行了广泛的研究。根据块体周边的M—t图划分了三个地震活跃期,由于曲线外推了块体周边积累的应变,据Ms≥4.0级的地震频度求得块体周边的b值为0.42—0.56。 块体周边的强震有成组孕育的特点,在一个周边上发生了Ms≥6.0级的地震后,数年内(一般不超过五年)在块体其它周边上常跟着发生Ms≥6.0级的地震。研究了块体周边Ms≥7.0级地震前的活动图象,发现震前“活动区”和“空白区”可能并存。最后阐述了块体周边地壳应力场的方向,并计算了块体周边的平均滑动速率。
This article has carried on the extensive research to Ordos block. According to the M-t map around the block, three seismic phases are divided. Since the curve extrapolates the accumulated strain around the block, the b value around the block is 0.42-0.56 according to the earthquake frequency of Ms≥4.0 . Strong earthquakes around the block have the characteristics of a group of gestation. After an earthquake of Ms≥6.0 on a periphery, within a few years (usually no more than five years), Ms≥6.0 level earthquake. The moving images before Ms≥7.0 earthquake around the block are studied, and it is found that the “active area” and the “blank area” may co-exist before the earthquake. Finally, the direction of crustal stress field around the block is expounded, and the average sliding velocity around the block is calculated.