西南地区地震观测井泉水温动态特征研究

Research on dynamic characteristics of water temperature in wells and springs for seismic observation in Southwest China

本文利用西南地区地震前兆台网记录的井泉水温数字观测资料,对水温各类动态特征进行研究,提取不同井水温各类观测动态及同井不同深度水温各类观测动态特征.收集整理了114个井泉水温观测台站的观测数据,结果表明,西南地区水温观测以中深非自流井为主,水温动态范围较大,热水和高温热水主要分布在川西和云南地区.西南井泉水温长期动态可大致分上升型、下降型和波动型三种,短期动态可大致分为短周期型、稳定型、固体潮型三种.研究区井水温的同震变化以下降居多,单个井水温对不同地震的同震响应存在优势响应方向,说明水温的同震特征更依赖于井孔自身观测条件的影响.通过对1966年以来西南地区36次MS≥5.9级震例总结的统计分析得出,西南地区水温前兆异常率达67%,上升型水温异常占比最大,且水温异常多属于短临异常.给出了MS≥5.9地震震前水温异常井的最大震中距的大致范围,并根据异常震中距-震级的G-R关系给出其定量关系,为今后西南地区中强地震的发生提取有用的水温前兆信息提供基础资料.

In this paper, using the digital observation data of wellspring water temperature recorded by the seismic geophysical network in Southwest China, the dynamic characteristics of water temperature are studied, and the dynamic characteristics of different well water temperature and different depths of the same well are extracted. The observation data of 114 well spring temperature observation stations are collected and sorted out. The results show that the water temperature observation in Southwest China is mainly in the middle deep non artesian wells. The dynamic range of water temperature is large, mainly including the normal temperature water and the low temperature water. The hot water and the high temperature hot water are mainly distributed in Western Sichuan and Yunnan. The long-term performance of water temperature in southwest well can be roughly divided into three types: rising type, falling type and fluctuating type, and the short-term performance can be roughly divided into three types: short period type, stable type and solid tide type. In the study area, the water temperature of a single well has a dominant response direction to the coseismic response of different earthquakes. It shows that the coseismic characteristics of water temperature are more dependent on the observation conditions of the borehole itself.Based on the statistical analysis of 36 earthquake cases with MS 5.9 or above in Southwest China since 1966, it is concluded that, the anomaly rate of water temperature precursor is 67% in Southwest China, and the ascending water temperature anomaly accounts for the largest proportion, and most of the water temperature anomalies belong to short-term and imminent anomalies.The maximum epicentral distance of water temperature anomaly wells before MS≥5.9 earthquake is given, and its quantitative relationship is given according to the G-R relationship between abnormal epicenter distance and magnitude, which provides basic data for extracting useful water temperature precursor information for the occurrence of moderate strong earthquakes in Southwest China in the future.