An electrical resistivity tomography survey was conducted to assess the subsurface conditions associated with the coseismic liquefaction phenomenon in the epicentral region following the M_w 5.8 Mirpur earthquake (Pakistan) on 24 September 2019. The Mirpur earthquake produced extensive coseismic liquefaction‐induced surface deformations, including: sand blows, ground failure and lateral spreading along the Upper Jhelum Canal and in the nearby villages. Electrical resistivity data were acquired along three profiles and calibrated with available borehole data. The inverted electrical resistivity tomography profiles reveal three regional geoelectric layers, which consist of an upper 2–‐5‐m‐thick discontinuous zones of medium resistivity values ranging from 25 Ωm to 60 Ωm, underlain by a 7–8‐m‐thick zone of low resistivity (<10 Ωm) and a basal layer of high resistivity (> 100 Ωm). Based on geological and geophysical data, we infer that. (1) disrupted geoelectric layers in the shallow subsurface and spatially extended low electrical resistivity (<8 Ωm) layers document the elevated groundwater table due to sudden increase in pore‐water pressure triggered by the Mirpur earthquake. These lenses of high conductivity may represent potential hazards in the case of future earthquakes in the study area. (2) Fracture azimuths vary between 120° ± 15° and 335°–45° (subparallel and orthogonal to the strike of the Himalayan Frontal Thrust. (3) Common coseismic deformational features (e.g., sand blow and ground fracture) are located within the zone of maximum‐recorded ground shaking (intensity of VI) and underlain by Quaternary alluvial sediments. (4) Mega fractures (1.60 m wide and up to 187 m long) oriented parallel to the canal resulted from lateral spreading. We conclude that high resistivity structures extending from depth to the shallow subsurface resulted from either intrusion of air or eruption of sands from layer three. We suggest that high‐resolution geoelectrical imaging is a valuable complementary tool for evaluating the extent of subsurface liquefaction features and in understanding coseismic deformation during earthquakes, which can help with seismic hazard analysis and mitigation in seismically active regions.

中文翻译：

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使用近地表电阻率层析成像和地质数据调查与2019年巴基斯坦Mur 5.8地震有关的同震液化引起的地面变形

进行了电阻层析层析成像调查以评估与M _w之后震中区域的同震液化现象相关的地下条件5.8 2019年9月24日，巴基斯坦米尔普尔地震。米尔普尔地震引起了广泛的由地震液化引起的地表变形，包括：沙漏，地面破坏和沿上耶赫勒姆运河及附近村庄的横向扩散。沿三个剖面采集电阻率数据，并用可用的井眼数据进行校准。反向电阻率层析成像剖面显示了三个区域性地电层，包括上层2–5–m–厚的不连续区域，中等电阻率值范围为25Ωm至60Ωm，下面是7–8–m厚的区域具有低电阻率（<10Ωm）和高电阻率（> 100Ωm）的基底层。根据地质和地球物理数据，我们可以推断出这一点。（1）浅层地下的扰动地电层和空间扩展的低电阻率（<8Ωm）层记录了由于Mirpur地震引发的孔隙水压力突然增加而导致地下水位升高的现象。在研究区域将来发生地震时，这些高电导率的镜片可能会构成潜在的危害。（2）断裂方位角在120°±15°和335°–45°之间变化（与喜马拉雅前冲的走向平行且正交）。（3）共同的同震形变特征（例如吹沙和地面破裂）位于内部第四纪冲积沉积物在地面上最大记录的地面震动（强度为VI）和底层（4）平行于运河的巨型裂缝（宽1.60 m，长187 m）是由侧向扩展引起的。我们得出的结论是，从深度延伸到浅地下的高电阻率结构是由于空气侵入或第三层沙层喷发造成的。我们建议高分辨率地电成像是评估地下液化程度和理解地震过程中同震变形的有价值的补充工具，可有助于地震危险区域的地震危险性分析和减震。