An improved glimpse into earthquake activity in northeastern Alaska

Abstract

The northeastern Brooks Range is long known to be seismically active, but meaningful analysis of the earthquake activity has been limited by the lack of instrumentation. The seismic record in the area dates back to the mid-1970s, and shows a broad northeast-trending zone of earthquake activity. Improvements made in the past 20 years to the permanent seismic network along with new data collected by the temporary USArray network of seismometers located throughout northeastern Alaska have dramatically lowered the earthquake detection threshold in the area. It is now possible to identify patterns within the earthquake data including spatial distribution and occurrence rates, which indicate the presence of previously unrecognized active fault systems. I highlight several such features within the data: a 110 km (60 mi) line of recurring earthquakes near the village of Beaver that strongly suggest a singular fault system; a cluster of earthquakes near the village of Venetie that are likely occurring on a complex active fault system; a years-long mainshock-aftershock sequence of earthquakes near the Draanjik River that began in 2006; and two swarms separated by 50 km (30 mi) in distance and 7 years near the Hulahula River.