青藏高原北部地震区弧形带与东缘带大地震活动特征的对比研究

CONTRASTIVE RESEARCH OF LARGE EARTHQUAKES ACTIVITY CHARACTERISTICS ALONG THE EASTERN EDGE AND ARCH BELT IN THE NORTH EARTHQUAKE AREA OF QINGHAITIBET PLATEAU

汶川8.0级地震前地震活动图像,呈现长期（几十年）多阶段中强震起伏和中长期（10-30年）强震活动平静,甚至无5级以上地震情况下突发大地震等显著特点。与青藏高原北部地震区大多数7级以上地震中期（几年至10年）中强震增多和中短期（1-3年）成组大震活跃等特点,形成鲜明的对照。将中国南北带东边缘带M≥7.7的11次大地震（含汶川8.0级）归属于中长期多阶段起伏、中短期突发型地震,相应的另一种大震称为中短期渐进型地震。围绕这一认识,对汶川8.0级地震活动特征作回顾性探讨。

The seismic activity pattern showed moderately strong earthquakes occurred ups and downs for a long period, strong earthquake activity kept calm for 10 to 30 years and large earthquake would occur suddenly even without moderate earthquakes above 5. On the contrary, in the north large earthquake area, there was moderate earthquakes increasing for ten years and large earthquakes occurred in group for 1 to 3 years before most strong earthquakes above 7. The author thought if 11 large earthquakes above 7.7 （ including Wenchuan 8.0 earthquake） in eastern edge of North-south earthquake belt belonged to ＂occurring ups and downs in medium or long term and suddenly in short term＂, the other kind of large earthquake should be ＂occurring step by step＂ correspondingly. The earthquake activity characteristics of Wenchuan 8.0 earthquake was reviewed and discussed on the base of the above thought.