大姚6.2级地震前中强震活动特征及短临预测意义

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。短时间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。

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

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 M_S 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.