Characterizing 6 August 2007 Crandall Canyon mine collapse from ALOS PALSAR InSAR

We used ALOS InSAR images to study land surface deformation over the Crandall Canyon mine in Utah, which collapsed on 6 August 2007 and killed six miners. The collapse was registered as a ML 3.9 seismic event. An InSAR image spanning the time of the collapse shows 25–30 cm surface subsidence over the mine. We used distributed dislocation sources to model the deformation field, and found that a collapse source model alone does not adequately fit the deformation field. Normal faulting is also required, such that the event is best characterized as a ‘trapdoor’ collapse. The calculated moment of the normal fault is about the same as the moment of the collapse source, with each larger than the seismically computed moment. Our InSAR results, including the location of the event, the extent of the collapsed area, and constraints on the shearing component of the deformation source, all confirm and extend recent seismic studies of the 6 August 2007 event.