Abstract

Seismic network coverage in Alaska has fundamentally changed with the presence of the USArray Transportable Array (TA) stations. These new stations provided an unprecedented opportunity to expand earthquake reporting in areas of Alaska that have not previously been instrumented. The Alaska Earthquake Center (AEC) has been incorporating all TA data into its standard earthquake analysis. The TA network is currently the second largest contributor of phase picks in the Alaska earthquake catalog, after the AK network operated by the AEC. Recent increases in reported earthquakes (about 45,000 in 2017 and 55,000 in 2018) are directly attributable to the additional TA stations, especially in the northern and western mainland Alaska. In some regions, the earthquake detection threshold decreased by as much as two units of magnitude. With the TA installation complete in 2017, the detection threshold over the entire mainland Alaska region is M1.5. The new stations have also led to a decrease in hypocentral location errors, which are now more uniform over the entire mainland Alaska region. The uniformity of the TA network made it possible, for the first time, to make quantitatively valid comparisons of microseismic activity in different parts of the state. Among other observations, this uniform coverage helped demonstrate that the quiescence that has long been inferred in the central and western Arctic Slope region appears to be real, and not just an artifact of network coverage. This combined network should, with time, provide vastly better data for seismic hazard assessments in an area of increasing national interest.

You do not currently have access to this article.