青海钻孔应变映震效能研究

Prediction Capability Analysis of Borehole Strain in Qinghai Province

摘要:

利用青海省6套YRY-4分量钻孔应变仪2007-2015年的观测资料，将该地区符合扫描范围的地震从震前异常和同震特征两方面进行研究。结果显示：湟源、德令哈分量钻孔应变差应变曲线地震前大多有短期超差异常；分量钻孔应变仪的同震响应幅度与震级、震中距都有关。同一地震，多台仪器多数情况同震响应幅度与震中距成反比，少数成正比；一般单台仪器同震响应幅度与地震震级成正比关系，震级越大同震响应幅度越大；分量钻孔应变仪的同震响应延迟时间大多与地震震中距成正比，震中距越远同震响应延迟时间越长；分量钻孔应变仪同震响应持续时间与震级基本成正比，震级越大同震持续时间越长。

Abstract:

Since 2007, component borehole strain observations have been carried out in Qinghai province. Because the observation environment is characterized by low interference levels and the observation instrument is stable, the observation data is continuous and reliable. During the observation period, several earthquakes with magnitude>6 occurred in Qinghai and the region nearby. To study the earthquake reflection ability of the borehole strain observation data, in this study, we analyze the observation data recorded by six 4-component borehole strainmeters in Qinghai from two aspects:the presence of anomaly prior to earthquakes and the coseismic characteristics. Our results show that the amplitude of the coseismic response of the 4-component borehole strainmeter bears a relationship to the magnitude and epicentral distance. In individual earthquakes, we found the coseismic response amplitude of multiple instruments to be inversely proportional to the epicentral distance in most cases and proportional in a few cases. The amplitude of the coseismic response of a single instrument is proportional to the general magnitude, whereby the larger is the earthquake magnitude, the greater is the amplitude of the coseismic response. The coseismic response delay time of the 4-component borehole strainmeter is mostly proportional to the earthquake epicentral distance, whereby the greater is the epicentral distance, the longer is the coseismic response delay time. The coseismic response duration of an instrument is basically proportional to the magnitude, whereby the greater is the magnitude, the longer is the duration of the coseismic response.