Potential of sinkhole precursor detection through interferometric SAR

Abstract

Sinkholes are an unpredictable geohazard that endangers life and structures in susceptible areas globally. Subsidence sinkholes occur above cavernous bedrock comprised of highly soluble evaporates or calcium carbonates such as dolomite or limestone. Their formation requires the erosion of regolith material into cavities leading to the collapse of the roof strata. The cavity formation and subsequent erosion is mainly due to groundwater extraction or the ingress of water, often from leaking services or poor storm water drainage [1]. Although sinkholes generally appear catastrophically with little warning, the appearance of tension cracks, cracks in infrastructure and surface subsidence are often early signs of sinkhole development. Such precursory deformation occurs weeks to years before sinkhole formation due to underground cavity migration. These precursors are key to an operational early warning system and detecting them is currently a major challenge for sinkhole hazard mitigation efforts [2]. However, the location and timing of sinkholes is typically unpredictable. The in situ monitoring of large areas for small scale subsidence is therefore not feasible.