Sunday morning at around 6:58 am local time there was a M6.4 earthquake on the North Slope of Alaska within the Arctic National Wildlife Preserve (ANWR). It was followed by a vigorous aftershock sequence that included a M6.0. These two events are the first and second largest ever instrumentally recorded north of the Brooks Range Mountains.
This area is not well understood due to its remote location, but luckily the Transportable Array project (by USArray) has provided a large number of seismic stations at an approximately even spacing, several of which were able to pick up this event. This data will be important to learn more about the structure of this understudied region. The stations plotted in black on the map are part of the USArray TA project.
Please see the Alaska Earthquake Information Center page for more information.