李新艳, 解滔, 曾宪伟, 崔瑾, 李霞. 0: 虚位错模式揭示的视电阻率在2022年1月8日门源6.9级地震前的响应. 地震学报.
引用本文: 李新艳, 解滔, 曾宪伟, 崔瑾, 李霞. 0: 虚位错模式揭示的视电阻率在2022年1月8日门源6.9级地震前的响应. 地震学报.
XinYan LI, Tao JIE, XianWei CENG, Jin CUI, Xia LI. 0: Changes of apparent resistivity before the 2022 Ms 6.9 Menyuan,Qinghai earthquake revealed by fault virtual dislocation model. Acta Seismologica Sinica.
Citation: XinYan LI, Tao JIE, XianWei CENG, Jin CUI, Xia LI. 0: Changes of apparent resistivity before the 2022 Ms 6.9 Menyuan,Qinghai earthquake revealed by fault virtual dislocation model. Acta Seismologica Sinica.

虚位错模式揭示的视电阻率在2022年1月8日门源6.9级地震前的响应

Changes of apparent resistivity before the 2022 Ms 6.9 Menyuan,Qinghai earthquake revealed by fault virtual dislocation model

  • 摘要: 2022年1月8日青海海北州门源县发生MS 6.9级地震,震中400km范围内存在9个视电阻率观测台站。本文选取观测质量高、具有稳态年变的视电阻率观测数据,结合ERA5同化数据集中的多层土壤温度和土壤水分,在利用多项式拟合获取各台站/测道视电阻率正常年动态、排除环境干扰的基础上,分析了视电阻率异常变化。结果表明,金银滩台EW测道、武威台NS测道、EW测道和山丹台EW测道、N45°W测道存在超阈值的异常变化,并呈现各向异性特征。基于断层虚位错模式发现,处于震前压缩区并受到NNE方向挤压的金银滩台,EW测道出现了负异常;同样位于压缩区武威台,视电阻NS道在孕震早期以负异常为主,孕震中晚期出现了正异常, EW道则在临震阶段出现了正异常;位于膨胀区的山丹台受到NS向的拉张,EW测道视电阻震前1年就出现超过2δ阈值的正异常,N45°W测道自2020年8月开始持续高值变化, 2021年8月超过阈值呈现正异常;定西台也位于膨胀区,视电阻率NS道在2020年9~11月的变化接近异常阈值。门源6.9级地震前视电阻率异常变化的时空特征与实验结果及理论模型一致,同时也符合震源区应力-应变积累程度较高、向外围方向逐渐衰减的分布特征。由此认为,门源6.9级地震前视电阻率的时空变化可能与区域介质变形及应力变化有关。

     

    Abstract: A major earthquake (Ms 6.9) struck the Menyuan county of Haibei prefecture, Qinghai Province, China. There are nine apparent resistivity observation stations within 400km of the epicenter. In this study, observation data with high quality and stable annual variation was selected to extract anomalies by removing the normal annual dynamics under the influence of soil water and soil temperature. The results show that the EW direction at Jinyintan station, the NS and EW direction at Wuwei station, and the EW and N45°W direction at Shandan station were found anomalies and exhibit anisotropic characteristics. According to the fault virtual dislocation model, a negative anomaly was found in EW direction of Jinyintan station, which is located in the pre-earthquake compression zone. Meanwhile, the NS direction of Wuwei station also showed mainly negative anomalies in the early stages of the earthquake preparation, but a normal anomalies was demonstrated in the late phase of strong earthquake preparation, while the EW direction shows a normal anomalies in the impending earthquake stage; A positive anomaly was observed with the EW direction of Shandan station one year prior to the apparent earthquake, and the array of N45°W direction has continued to be quite positive since August 2020, and exceeding the threshold value in August. The NS direction of Dingxi station is also in the expansion zone, and it is close to the abnormal threshold from September to November ,2020. In accordance with the experimental results and theoretical models, the temporal and spatial characteristics of the variation of apparent resistivity before the Ms6.9 Menyuan earthquake are consistent with the accumulation of stress-strain in the epicenter and gradual attenuation toward the periphery. Therefore, the spatio-temporal variation of apparent resistivity before the Ms6.9 Menyuan earthquake may be related to regional medium deformation and stress state.

     

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