Contributions of USArray Stations to Regional Earthquake Monitoring in Alaska

Date: 4/26/2019

Time: 04:00 PM

Room: Cascade II

Alaska is the most seismically active state in the nation with earthquakes spanning tectonic regimes, including transform faulting in the southeast Alaska, collision in the St.Elias region, subduction in southern Alaska and along the Aleutian Island Arc, and complex crustal faulting extending north to the Beaufort Sea. As a result of this tectonic complexity, earthquake detection in Alaska is non-trivial. Automatic earthquake detection and review procedures have existed at the Alaska Earthquake Center for decades. The procedures have been calibrated to measure as much seismicity as feasible while minimizing errors and workload. In the last three years, the seismic station coverage in Alaska has grown significantly with the presence of the USArray TA stations. The TA stations have provided an unprecedented opportunity to expand earthquake reporting in areas of Alaska that have never been instrumented. The Alaska Earthquake Center has been incorporating all TA data into its routine earthquake analysis. Recent increases in the number of reported earthquakes (over 50,000 in 2018) can be correlated with additional TA stations, especially those installed in the northeast Brooks Range, Bristol Bay region and interior Alaska. As a result, the magnitude detection threshold in these regions has decreased from M~3.0 to M~1.5. In recent months, phase picks from TA stations totaled about 30,000 per month (or about 30% of the total picks). The only region of Alaska that lacks earthquake detections despite TA station presence is north of the central and western Brooks Range, or so called North Slope region. This presentation will assess the quantitative changes in earthquake reporting that have occurred because of the inclusion of data from the TA stations and highlight recent notable Alaskan earthqukes.

Presenting Author: Natalia Ruppert

Authors