澜沧7.6级地震前云南地电台网地电阻率变化特征

FEATURES OF EARTH RESISTIVITY CHANGES IN THE YUNNAN GEOELECTRIC OBSERVATION NETWORK BEFORE THE M7.6 LANCANG EARTHQUAKE

1988年11月6日我国云南澜沧发生7.6级强烈地震,震前云南地电台网出现了地电阻率的异常变化。本文分析了这些异常特征。它的整个变化过程大体可分为三个阶段,第一阶段为长期趋势异常起始于1984年,第二阶段为中期趋势异常从1987年开始;第三阶段为短临异常大约震前半年左右开始。这些变化特征不但澜沧地震前有,在其他一些强震前亦有一定显示。识别这些阶段变化特征,对今后的强震监视是会有其一定实用价值的。

A strong earthquake of M7.6 struck Lancang, Yunnan Province on November 6, 1988, and abnormal earth resistivity changes were detected in the geoclectrie observation networks in Yunnan Province. This paper analyses the features of such anomalies, the process of variations of which can basically be classified into 3 episodes. The first episode starting 1984 shows long-term of tendency anomalies. The second episode starting 1987 presents features of midterm anomalies. The third episode starting approximately 6 months before the earthquake shows features of short-term and impending anomalies. Such features of anomalous changes are not only observed before Lancang earthquake, but also detected to a certain extent before a number of other strong events. Identification of the characteristics of such episodic changes might be of sonic practical value lor the monitoring of strong events in the future.