RADARSAT-2 DInSAR and GNSS-Derived Finite Fault Model of the 2012 Mw 7.8 Haida Gwaii Earthquake

The Mw 7.8 Haida Gwaii earthquake occurred on 28 October 2012, generating up to 13 m tsunami waves and 3 m run-up along the British Columbia coastline. Despite the magnitude of the earthquake and tsunami, damages were minor due to the lack of vulnerable infrastructure in the remote area. Previous finite fault models were derived from GNSS, seismic and tsunami data, but the uncertainty remained high due to the limited number of seismic and GNSS stations near the epicenter. In this study, finite fault models were developed using RADARSAT-2 interferograms and previously published GNSS data. These models defined the location of the fault and provided a detailed slip distribution with a high degree of certainty. The results confirmed that the main slip was located on the subduction fault interface between the Pacific and North American plates, west of the Queen Charlotte Fault. The estimated moment magnitude of 7.88–7.93 is slightly larger than the previously reported moment magnitude of around 7.8, due to the capture of postseismic deformation in the interferograms. Overall, the study provides an improved finite fault slip model for the Haida Gwaii earthquake and highlights the importance of utilizing remote sensing data for studying earthquakes in remote areas.