Sinkholes in gypsarenites embedded within siliciclastic successions: the Belforte del Chienti example (Italy)

Ernesto Paolo Prinzi¹, Stefania Nisio¹, Diego Di Martire², Vincenzo Allocca², Luigi Guerriero², Marco Nocentini¹ & Angelo Cipriani^1
1Department for the Geological Survey of Italy – Institute for Environmental Protection and Research (ISPRA).
²Department of Earth, Environmental and Resource Sciences – University of Naples "Federico II".
Corresponding author e-mail: ernestopaolo.prinzi@isprambiente.it

Previously undocumented sinkholes were identified during geological field mapping for Sheet 313 “Camerino” (1:50,000 scale, CARG) within Messinian gypsarenite layers embedded in a dominantly siliciclastic succession at Belforte del Chienti (MC, central Italy). In the study area, where arenaceous and clayey lithotypes of the Laga Basin prevail, sinkholes are extremely rare, as also reflected by their scarce representation in national databases and the scientific literature. Geological field data, integrated with geognostic boreholes stratigraphies, allowed the construction of a preliminary geological model of the area, which was further refined using InSAR data from the surrounding areas. The latter revealed localized ground deformations over the satellite observation period that may be associated with, or influenced by, the presence of the study sinkholes. These subsidence structures have significantly altered the surface and subsurface hydrological flow, perturbing the pre-existing equilibrium of slopes already affected by landsliding. In addition, the high susceptibility to erosion of the investigated gypsarenite horizons may be enhanced by water losses from pressurized distribution networks and by irrigation practices. Satellite data analysis highlights ground movements potentially linked to the presence or activity of sinkholes. This case study is scientifically relevant due to its uniqueness within this lithostratigraphic and structural context and its implications for hazard assessment. The risk of further collapses or the evolution of existing cavities is particularly critical given the proximity of infrastructures, including roads and buildings, which increases exposure of human and material assets. Targeted geophysical and hydrogeological investigations could help identify collapse-prone cavities in areas with similar lithostratigraphic and structural characteristics, which may extend over several square kilometers. The aim of this study is to analyze and classify these sinkholes and to evaluate the potential hazards affecting the nearby residential area.

sinkhole, evaporites, karst, collapse, Marche Region.