Monitoring dewatering induced subsidence and fault reactivation using interferometric synthetic aperture radar

Abstract

Using multitemporal differential interferometric synthetic aperture radar analysis integrated with pumping and site geologic data we present evidence for hydrologically induced large subsidence in and around an ongoing open‐pit mine with intensive dewatering operations. Analysis of numerous differential synthetic aperture radar interferometry (DInSAR) pairs spanning the period 1993 to 2001 reveals the abrupt appearance of these features to intervals of a few to several months. Along a section through the anomaly, we plotted dewatering associated changes in the groundwater levels at monitoring wells. We also used DInSAR to extract several individual kilometre‐lengths, centimetre amplitude normal fault reactivation events in the alluvial sediments adjacent to the mine dewatering operation. High‐resolution remote sensing analyses provide strong evidence that these features align with faults active in the last several thousand years. We interpret these reactivations as mechanically involving only the upper few hundred metres of the existing fault plane above the alluvial aquifer affected by the mine dewatering.