大姚6.2级地震前中强震活动特征及短临预测意义

Characteristic of mid-strong seismic activity before M 6.2 Dayao earthquake and its significance for short-term and immediate earthquake predication

在不到4年的时间内，云南作为中国西南能量释放的主体地区之一，发生了令全世界地震学家瞩目的地震现象。2001年3～10月，云南中强地震频发，超出平均年频次3倍，总数占全国的50％。此后632天5．0级以上地震罕见平静。短时问内的高频度中强震后，紧接着极度的平静，这在中国地震史上极其少见。云南省地震局高度重视，采取了一系列的措施：加密观测，加强会商，及时落实宏观异常，加强分析力量，对2003年7月21日大姚6．2级地震作出了较好的预报。文章对大姚6．2级地震事件的前前后后及预报过程做了详细描述，并提出了一些可供参考的观点。

As one of regions released most earthquake energy in southwestern China, Yunnan has been focus attention upon the seismologists among the world for the seismic activity occurred there last 4 years. From March to October 2001, strong earthquakes occurred frequently. The frequency is three times larger than the annual average. The number of earthquakes is about 50% of total in all country. After that, a near two year, 632 days actually, abnormal quiet period of time for earthquake of M〉 5.0 followed. The occurrence of high frequent medium-strong earthquakes in short term with a followed extremely quiet period is a singular phenomenon of earthquake history in China. The seismological bureau of Yunnan province paid much attention to this phenomenon, and adopted a series of measures, including increasing observation, enhancing consultation, verifying macroscopic anomalies in time and enforcing analytic capability. As a result, the Dayao Ms 6.2 earthquake on July 20 was forecasted successfully. In this paper, the forecast procedure before and after the Dayao M 6.2 earthquake is described in detail, and some viewpoints are presented for future reference.