北京市延庆地震台地电阻率长程观测数据研究

分析北京延庆台1988年以来地电阻率观测资料的可靠性,讨论归一化变化速率方法,用以处理该台地电阻率长程观测数据;结合北京及邻近地区近三十年来发生的7次中强地震,研究该台地电阻率异常与地震的对应关系。结果表明:延庆台地电阻率观测对附近的中等以上地震和远距离大震有一定的映震能力,可为今后该台附近及邻近地区的地震提供中、短期预测预报参考依据;同时该台在中国大陆及周边远距离大震前也观测到了时间上对应的地电阻率异常。

Long-term Observation Data of Geo-electrical Resistivity at the Yanqing Station, Beijing

The Yanqing station in Beijing has observed geo-electrical resistivity for almost 30 years.This station started observing the Geo-electrical resistivity in 1969 and a technological transformation of this observation site occurred in 1988.The station has roughly conducted normal observations since 1988.However,some environmental interference has occasionally occurred in the station''s electrode-arranging region.This station is one of the few stations affected by environmental interference in the Beijing,Tianjin,and Tangshan areas.The quality of geo-electrical resistivity observation data has had relatively high standards for a long time.The reliability of geo-electrical resistivity observations since 1988 at the Yanqing station was analyzed. The normalized variation rate method was applied to process long-range geo-electrical resistivity observations.Data from seven medium or strong earthquakes that occurred near Beijing were integrated to study the relationship between geo-electrical resistivity and earthquakes.The results showed that the abnormal changes in geo-electrical resistivity observations demonstrated two characteristics of apparent resistivity changes.The first characteristic was an observation that appeared for a medium or short period and abnormal changes continued before the medium earthquakes occurred.The second characteristic was observed as an observation that had a long term of about 1 year and continued to have higher or lower abnormal changes before strong earthquakes occurred.This revealed a compact temporal correlation between the abnormal changes and strong earthquakes.The geo-electrical resistivity observation at the Yanqing station has the ability to reflect strong earthquakes near the station.Therefore,the observations provide a frame of reference for long-term or short-term earthquake prediction in nearby areas.In addition,the geo-electrical resistivity observations changed abnormal while strong earthquakes were occurring at long distances from the station in or around China.This showed that the geo-electrical resistivity observation at the Yanqing station can also be used to study earthquake prediction over long distances.The normalized variation rate method was applied to process the monthly observations of geo-electrical resistivity.This is an effective method to extract long-term or short-term geo-electrical resistivity data for abnormal changes.The abnormal changes that cannot be identified from the monthly data series can also be easily discovered through this normalized variation rate process.