台湾地区7级强地震前中强地震条带特征讨论

分析了我国台湾地区近期的地震时空分布，发现从1993年开始，台湾地区MD5．5级^①以上地震逐渐形成了二条相交于花莲、苏沃海外的中强地震条带，其中一条呈北东向分布，另一条呈北西向分布，一直持续到1999年9月21日北东向条带西南段的空段附近(南投)发生了MS7．6级强震群型地震后仍然存在，结果2002年3月31日又在两条条带交汇处的苏沃海外发生了MS7．5级主震型地震。与板内地震条带相比：组成这两条条带的地震震级较大(大于5．5)；这两条条带的长度较短(不到400km)；北西向条带在后期的地震数量偏少；北西向条带的长宽比也较小(小于5)。

Discussion on the characters of medium - strong seismic belt before strong earthquake with magnitude 7 in Taiwan region

The spatial and temporal distribution of the recent earthquakes in the Taiwan area has been analyzed in the paper. The author finds earthquakes over M_D5.5 gradually have formed two medium-strong seismic belt intersecting at Hualian and Suao abroad since 1993.One extends in NE direction, the other extends in NW direction. The two belts had existed until the strong swarm-type earthquake with M_S7.6 occurred near the gap, namely Nantou, at the WS segment of the NE belt on Set 21, 1999. The main shock type earthquake with M_S7.5 occurred again in Suao where is the intersecting portion of the two belts on Mar 31, 2002. Comparing with intraplate belts, the two belts are shorter than 400km, the earthquake magnitude are greater than M 5.5, the earthquake number of NW belt is fewer and it 's ratio of length and width are also less than 5.