Development and Mechanism of Ground Fissures in Xiong County, North China Plain: A Primarily Human-Induced Case Study

The North China Plain is one of the most representative regions globally for ground fissure development. In particular, the Xiong County ground fissures have repeatedly reopened despite remediation, causing serious socio-economic impacts, yet their formation mechanism remains unclear. This study systematically investigates their development characteristics and controlling factors using integrated methods, including field survey, trenching, geophysical exploration, drilling, laboratory testing, and Interferometric Synthetic Aperture Radar (InSAR) analysis. Results show that the fissures generally trend between 0° and 20° and occur mainly in forested areas. In planar view, they appear as horizontal tension cracks and collapse pits, while in profile they are nearly vertical, extend to depths greater than 30 m, widen upward and narrow downward, and are filled with heterogeneous soils, with no significant vertical displacement of the strata on either side. The fissures are controlled by multiple factors: thick Quaternary deposits (>300 m) provide the material basis; early activity of the Niuxi Fault formed a concealed fissure system; repeated land modification and soil disturbance enhanced the collapsibility of near-surface soils; and differential subsidence caused by groundwater overextraction, together with soil shrinkage, promoted fissure propagation. Finally, rainfall infiltration and erosion exposed fissures at the surface, while phreatic water erosion enlarged them and triggered recurrent reactivation. These findings clarify the formation mechanism and evolution of human-induced ground fissures in the North China Plain and support hazard mitigation in similar settings.