摘要
通过数值模拟及褶积滤波方法,对甘肃省定西台地电阻率两测道“冬低夏高”的反向年变形态进行分析,并利用自适应计算变化幅度法提取该台地电阻率资料的中短期异常数据。结果表明,定西地电阻率的年变形态主要受地表薄层介质电阻率季节变化和降雨影响;褶积滤波法可以拟合短期降雨影响,并且可以过滤地电阻率的年变形态,但2021年出现的趋势性转折下降的低值破年变与降雨量和薄层季节干扰关系不大;九寨沟7.0级和门源6.9级地震前出现较为显著的中短期下降异常变化,最大下降率为0.983%;2022年门源6.9级地震后的两测道去年变趋势变化幅度中的异常形态依然存在,且并未恢复。因此定西台地电阻率对甘东南和祁连山中东段具有指示意义,有必要利用该方法进一步重点关注该区域的强震危险性。
In this study,the reverse annual variation of“low values in winter and high values in summer”in two measuring channels of geoelectrical resistivity at Dingxi station was analyzed using numerical simulation and convolution filtering,and the medium-and short-term anomalies of the resistivity data were extracted using the adaptive variation amplitude method.Results show that the annual variation of geoelectrical resistivity at Dingxi station is mainly influenced by seasonal variation and rainfall.The convolution filtering method can fit the effect of short-term rainfall and remove the annual variation of geoelectrical resistivity.However,the low values breaking the annual variation in 2021 have minimal relation with the rainfall and seasonal interference.Before the Jiuzhaigou M 7.0 earthquake in 2017 and the Menyuan M 6.9 earthquake in 2022,a significant short-to-medium term decline anomaly with a maximum decline of 0.983%appeared.After the Menyuan M 6.9 earthquake in 2022,the abnormal pattern in the variation amplitude still exists even with the annual variation removed in the two channels.From the perspective of spatial characteristics,the geoelectrical resistivity at Dingxi station is indicative of the southeast Gansu and the middle-east section of the Qilian Mountains,so attention should be paid to the strong earthquake risk in these areas.
作者
张丽琼
李娜
ZHANG Liqiong;LI Na(Gansu Lanzhou Geophysics National Observation and Research Station,Lanzhou 730000,Gansu,China;Gansu Earthquake Agency,Lanzhou 730000,Gansu,China)
出处
《地震工程学报》
CSCD
北大核心
2023年第3期565-573,共9页
China Earthquake Engineering Journal
基金
兰州地球物理国家野外科学观测研究站项目(2021Y01)
中国地震局震情跟踪定向工作任务(2022010411)。
关键词
地电阻率
反向年变
褶积滤波
异常特征
定西台
geoelectrical resistivity
reverse annual variation
convolution filtering
abnormal characteristics
Dingxi station
