门源、共和地震前甘青交界地区浅层地温异常时空分布特征

THE SPACE-TIME DISTRIBUTION FEATURES OF SHALLOW GEOTEMPERATURE ANOMALY INTHE BOUNDARY REGIONS BETWEEN QINGHAI AND GANSU PROVINCES BEFORE THE MENYUAN AND GONGHE EARTHQUAKES

本文研究了,1986年门源6.4级地震和1990年共和7.0级地震前,1980-1990年青海省东北部甘青交界地区浅层地温场的时空分布特征。主要结论如下:门源地震前,1985年出现以青海湖为中心的浅层地温增温区,其中从湟源—门源一带形成椭圆形地温高值区,1986年该增温区地温下降;共和地震前从1987年开始出现大面积、长时间浅层地温增高区。增温幅度较大的地区集中在青海省湟源—共和—兴海一线。距震中区较远处增温早、幅度小;震中区附近增温出现晚,增温幅度大;临震前浅层地温出现突升—突降的波动特征。

In this paper,the space-time distribution features of shallow geotemperature field in the boundary regions between Qinghai and Gansu Provinces during 1980-1990 before the Menyuan earthquake Ms=6.4 of 1986 and Gonghe earthquake Ms=7.0 of 1990 are studied.The main conclusions are as follows:In 1985,before the Menyuan earthquake,there appeared the shallow geotemperature rising, region,centered in Qinghai Lake,forming a elliptic area from Huangyuan to Mengyuan, and in 1986 the geotemperature value of the rising region decreased.From 1987,before, the Gonghe earthquake,there appeared, the rising region of shallow geotemperature with large and long time, concentrated in Huangyuan-Gonghe-Xinghai of Qinghai.In the region far from seismic centre,the geotemperature value went up early,and was small amplitude;nearby the epicenter,the geotemperature increasing was late but its amplitude was large.Immediately before the earthquakes,the shallow geotemperature showed undulating feature of sudden rising-sudden dropping.