The August 2018 Kaktovik Earthquakes: Active Tectonics in Northeastern Alaska Revealed With InSAR and Seismology

Abstract

The largest earthquakes recorded in northern Alaska (Mw 6.4 and Mw 6.0) occurred ∼ 6 hr apart on 12 August 2018, in the northeastern Brooks Range. The earthquakes were captured by Sentinel-1 interferometric synthetic aperture radar (InSAR) satellites and Earthscope Transportable Array seismic data, giving insight into the little-known active tectonic processes of Arctic Alaska, obscured until recently by sparse data availability. In this study, InSAR modeling, teleseismic back projections, calibrated hypocentral relocations, and regional moment tensor solutions resolve two previously unknown, SSW dipping right-lateral fault segments. These are the first active faults identified as conjugate to the NE trending sinistral Canning displacement zone directly to the west, which is therefore a more complex zone of diffuse faulting than previously thought. The northeastern Brooks Range has been characterized as an area of low to moderate seismic hazard, but these earthquakes illustrate the potential for larger, possibly destructive events in a region earmarked for rapid resource development.