泸定MS6.8地震前地电阻率的异常特征研究

Characteristics of Anomalous Evolution of Ground Resistivity in Sichuan Region before the Luding MS6.8 Earthquake

摘要:

对泸定M_S6.8地震前四川地区的地电阻率异常演化特征进行总结,发现不同时间阶段出现了不同的异常形态,主要有:①甘孜站、江油站、红格站3个台站在强震发生前的1～4.2年出现了长趋势变化的转折,目前多数测项已显示为持续性的趋势上升;②出现长趋势转折变化后,红格站、江油站分别在2020年11月、2021年4月出现了年变幅减小的现象;③甘孜站、江油站、冕宁站3个台站在泸定6.8级地震前出现了较为明显的中短期异常变化,震后3个台站的异常恢复,且再未出现此类异常变化。综上,长趋势变化的转折可能表明未来一段时间区域内强震风险升高,而加速上升/下降、反向变化等异常特征可能更具有中短期的指示意义。

Abstract:

By analyzing the anomalous evolution of ground resistivity in the Sichuan region before the Luding M_S6.8 earthquake,distinct abnormal patterns were observed at different stages. The key findings are as follows:(1)Long-term trend reversals occurred at Ganzi,Jiangyou,and Hongge stations 1-4.2 years before major earthquakes,with most measurement indicators currently exhibiting a sustained upward trend.(2)Following these long-term trend shifts,Hongge and Jiangyou stations experienced reductions in annual variation in November 2020 and April 2021,respectively.(3)Significant short-term anomalies were detected at Ganzi,Jiangyou,and Mianning stations just before the Luding earthquake,after which these anomalies disappeared and did not recur. In conclusion,long-term trend shifts may indicate an increasing risk of strong earthquakes,while features such as accelerated rises/falls and sudden reversals could serve as more indicative signals in the medium to short term.