云南地区震前地下流体异常特征统计分析

Statistical analysis of pre-seismic anomalous characteristics of subsurface fluids in Yunnan region

  • 摘要: 依据 《中国震例》 资料,统计分析了云南地区1966—2006年MS≥5.0地震的地下流体测项异常,结果表明:超过70%的水位和水温震前异常表现为上升,水氡和水位异常出现时间最早;震级越大相应的流体异常范围就越大;大多数震前流体异常会持续到地震发生,说明流体异常与震前地壳活动有关,并据此得出云南地区地震发生时间及异常检测井至震中距离的经验性边界方程。分类汇总云南地区地下流体测项的异常形态,识别出该地区地下流体异常的5种主要异常形态,即趋势转折类、周期类、突变类、阈值类和综合类,并举例阐明了各种异常形态的特征及其可能的成因。本文研究结果对于认识云南地区流体异常特征以及提升流体异常应用水平具有一定的参考意义。

     

    Abstract: Based on the information collected from the Earthquake Cases in China from 1966 to 2006, this paper carries out a statistical analysis of the subsurface fluids precursory anomalies of MS≥5.0 earthquakes in Yunnan Province. The results showed that: ① More than 70% water level and water temperature anomalies were observed rising before the earthquakes, and radon and water level anomalies appeared much earlier than temperature anomaly. ② The larger the earthquake magnitude, the larger the corresponding anomaly area of the fluid. ③ Most pre-seismic fluids anomalies persist until the earthquake occurs, indicating that they were related to pre-earthquake crustal activity, and a set of empirical boundary equations were obtained in an attempt to assist in the future earthquake prediction. Five types of groundwater anomaly were identified according to the summary of the abnormal morphology of groundwater, including trend turning class, period class, mutation class, threshold class and synthesis class, and typical cases, as well as possible reasons for each type were presented. The results of this paper could be helpful for understanding the abnormal characteristics of fluid and improving the application of fluid anomaly in the Yunnan region.

     

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