PRECURSORY AND COSEISMIC CHANGES IN GROUND RESISTIVITY
PRECURSORY AND COSEISMIC CHANGES IN GROUND RESISTIVITY
复制标题
地面电阻率的前兆和同震变化
DOI：
10.4294/jpe1952.25.supplement_s161
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发表时间：
1977
期刊：
影响因子：
--
通讯作者：
Y. Yamazaki
中科院分区：
文献类型：
--
作者：
T. Rikitake;Y. Yamazaki
自1968年以来，东京以南约60公里的地壳运动观测站一直在使用一台灵敏度极高的电阻率变感仪。该变感器记录与潮汐负荷有关的地壳应变引起的地电阻率变化。当大地震发生时，变感器经常记录到一个阶跃变化。对于8级或8级左右的地震，即使震中距离超过1000公里，也会观察到台阶。东京地区5级以上的地震也是如此。详细的调查表明，变感器似乎可以检测到电阻率阶跃形式的极小同震应变。电阻率阶跃通常在具有几个小时的前驱时间的瞬时变化之前。对21个实例的威布尔分布分析表明，控制前兆时间分布的特征参数与控制地表形变、倾斜应变、地下水等一组短期前兆的特征参数基本相同。这种电阻率的变化可能反映了震源区发生了前兆性破裂，对地震的短期预报有重要意义。
A resistivity variometer of unusually high sensitivity has been in operation at a crustal movement observatory about 60km south of Tokyo since 1968. The variometer records changes in ground resistivity caused by crustal strain in association with tidal loading. When a large earthquake occurs, the variometer often records a step-wise change. Steps are observed for earthquakes having a magnitude of 8 or thereabout even if the epicentral distance exceeds 1, 000km. It is also the case for earthquakes of magnitude about 5 or more in the Tokyo area. Detailed investigations indicate that the variometer seems likely to detect extremely small coseismic strains in the form of resistivity steps. The resistivity steps are often preceded by a precursory change having a precursor time of a few hours. A Weibull distribution analysis of 21 examples brings out that the characteristic parameter controlling the distribution of precursor time is more or less the same as that for a group of short-term precursors such as land deformation, tilt and strain, and underground water. This kind of resistivity change, that may probably reflect an occurrence of premonitory rupture in the focal region, seems to have an important bearing on short-term earthquake prediction.