Tracking surface and subsurface deformation associated with groundwater dynamics following the 2019 Mirpur earthquake

Abstract

The Mirpur Mw 5.8 earthquake on September 24, 2019, produced extensive liquefaction-induced surface deformation (LISD) in the surrounding villages. Due to the complexity of seismic hazards and the occurrence of their effects on a large spatial scale, the resulting surface, and subsurface deformation are often poorly resolved. To cover spatially extended LISD, the PSInSAR technique provided subsidence and uplift rate values ranging from −110 to +145 mm/yr consistent with the spatial distribution of the mapped liquefaction features. The most prominent surface change occurred in Abdupur and Sang villages. GPR measurements were conducted to map the near-surface cracks produced by transported liquified sand into the shallow subsurface layers and other liquefaction features (elevated groundwater table, conductive clay pockets, fractures, sand dikes, and water-enriched zones). Thus, the GPR survey assisted in the reconstruction of these structural and hydrogeological features on the near surface. In addition, the highly vulnerable zones were identified and mapped using space- and ground-based remote sensing measurements supported by the field observations. The results highlight the effectiveness of the proposed novel approach for detailed assessment of the coseismic liquefaction-induced deformation on- and near-ground surfaces by identifying areas prone to failure during earthquakes and thereby can help with hazard mitigation.