Radar could provide warning of sinkholes

Ars Technica : Sinkholes form when water dissolves minerals and erodes earth to create cavities under Earth’s surface. There’s little warning before the ground collapses. An analysis of data collected by NASA’s Uninhabited Airborne Vehicle Synthetic Aperture Radar by Cathleen Jones and Ron Blom of the Jet Propulsion Laboratory suggests that radar may be able to detect sinkholes before they collapse. The researchers examined two years of interferometric synthetic aperture radar (InSAR) maps collected in the area of a massive sinkhole near Bayou Corne in Louisiana. InSAR is sensitive enough to measure centimeter-sized shifts in ground elevation and is used to map movements of glaciers and fault lines. Jones and Blom detected a 25-cm horizontal shift in the area over the Bayou Corne sinkhole, which they believe was caused as loose soil fell into the gaps being created below it. Looking for similar ground movements could provide warning of future sinkholes.