Abstract

Catastrophic sinkholes are formed through the collapse of natural or human-made subterranean caverns, and are common in areas with evaporite and carbonate rock. Despite their danger, advance warning of these events is rare. We report a measurement of precursory surface deformation of as much as 260 mm, derived with interferometric synthetic aperture radar (InSAR) and evident over a month before surface collapse, at the site of the Bayou Corne, Louisiana (USA) sinkhole that formed in August 2012. Data collected by the airborne Uninhabited Aerial Vehicle SAR (UAVSAR) instrument were used for the study. Analysis of data acquired from two flight tracks with near-opposing imaging geometries reveal a deformation pattern consistent with compressive loading at the surface due to loss of support from a subterranean cavity collapse related to Texas Brine Oxy Geismar Well #3. The precursor deformation was nearly entirely horizontal, i.e., oriented along the surface, and manifested as movement of surface material toward the location where the sinkhole later formed. The sinkhole formed in the area with the largest gradient in surface strain, but did not cover the full extent of the precursory deformation detected with radar. This work suggests that InSAR data collected operationally for hazard monitoring could, in some cases, identify sinkhole development before surface collapse, and decrease subsequent danger to people and property.

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