Influence of fault properties and fold structures on karst sinkholes formation and evolution: Insights from a multidisciplinary analysis

Sinkholes are a widespread geological hazard in karst landforms, posing significant threats to human activities and infrastructure. While faults broadly influence sinkhole formation and evolution, few studies have addressed how specific fault characteristics and their interactions with fold structures impact groundwater recharge and sinkhole formation locally. This study employed a multidisciplinary approach, encompassing field investigation, geophysical surveys, hydrochemical analyses, and groundwater monitoring to investigate the anomalous ground vibrations observed over recent decades in Zhangjing Village, Hunan Province, China. Our findings revealed that the spatial and temporal distribution of sinkholes is predominantly structurally controlled by NNE-trending fault and fold systems. These geological features shaped a fault-bounded uplift geological framework that establishes intricate hydrogeological pathways. Strike-slip faults intersecting anticline structures facilitate the downward recharge of epigene aquifers into hypogene carbonate aquifers, whereas reverse faults in the discharge region acted as substantial hydraulic barriers, limiting lateral groundwater flow in the hypogene aquifer and promoting upward recharge into epigene aquifers. Further analysis indicated that the persistent ground vibrations in Zhangjing Village can be attributed to karst air blasting triggered by rapid groundwater level rises (about 30 m) after short-term heavy rainfall following prolonged droughts. This process ruptured cavity roofs and exceeded overburden stability thresholds, generating clustered cover collapse sinkholes. This work proposes a novel theoretical framework for fault-fold-groundwater interactions in karst sinkhole formation.