Early considerations and estimates for the performance of an Alaska-based earthquake early warning system

Abstract

The complexity of Alaska presents several challenges for earthquake early warning systems. These include the presence of offshore earthquakes, transform boundaries and crustal faults extending hundreds of kilometers, deep earthquakes, and a complicated coastline. This variety, combined with population centers spread far apart, makes it challenging to anticipate an earthquake early warning system's performance and to design a network accordingly. As Alaska begins to plan for earthquake early warning, our objective is to envision how and how well it might function in Alaska. We present here sets of scenarios with warning time and ground motion estimates for a variety of communities. These scenarios are designed to be meaningful test cases for Alaska earthquake early warning while also exploring how changes in source characteristics--such as magnitude, depth, location, and fault system--impact the timeliness of warnings. We combine travel time estimates, source time models, and the current seismic network to model hypothetical detection and alert times. We compare warning times to peak ground motions to determine the warning effectiveness. Our results suggest the potential for timely warnings up to Modified Mercalli Intensity 6 in the case of shallow earthquakes. More ideal scenarios, including deep earthquakes, could receive advanced warning for shaking up to intensity 8. Informed by these results, we discuss where we expect an Alaska earthquake early warning system to excel and what challenges should be tackled to improve other areas. Finally, we offer ways in which our results and insights can inform future works related to earthquake early warning in Alaska.