Collaborative Research: The M7.8 Simeonof earthquake: Untangling Slip from Seconds to Years across the edge of the Shumagin Seismic Gap

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The largest earthquakes on the planet occur where one plate pushes beneath another. In the United States, these earthquakes happen most frequently in Alaska, making that an ideal place to learn about how earthquake faults behave. This collaborative research project will study the recent 22 July 2020 Simeonof earthquake, located in the Shumagin Islands, Alaska, to learn about the character of fault slip before, during, and after earthquakes. They will determine the distribution of fault slip during and following the earthquake, and compare it with the distribution of fault slip before the earthquake. They will also use data from the Alaska Amphibious Community Seismic Experiment to more precisely locate the plate interface, where the slip occurs. The project will also develop training materials related to earthquakes for elementary students in partnership with local elementary schools.The researchers will collect three types of data, plus use data provided by NSF’s GAGE facility. They will measure the locations of survey markers on several islands of Alaska’s Shumagin Islands, and install continuously operating GPS sites at several of those locations. These data will show how much the ground moved permanently due to the earthquake and due to ongoing post-earthquake slip. They will complement these measurements with measurements of ground movements from repeat-pass satellite radar interferometry. Finally, the researchers will use seismic data from the Alaska Amphibious Community Seismic Experiment to locate earthquakes on the plate interface more precisely, and to use earthquakes within the downgoing Pacific plate to determine the location and geometry of the plate interface.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.