Seeking understanding of the fundamental constraints on plate motions, rates of convergence, and shallow strain accumulation across one of the United States’ most hazardous fault zones.
Unlocking plate motions of the Cascadia subduction zone with seafloor geodesy
USGS scientists from the Earthquake Hazards and Coastal Marine Hazards and Resources Programs have joined forces with academic colleagues (Scripps Institution of Oceanography, University of Washington, University of Hawai‘i/University of Stuttgart) in a pioneering effort to instrument the seafloor in the Pacific Northwest. The goal is to understand where and how much strain is accumulating along shallow portions of the Cascadia subduction zone that have produced large earthquakes and tsunamis in the past. From March 12-17, two new seafloor geodetic sites, each consisting of three seafloor benchmarks, will be placed on the seafloor to measure small (centimeter-scale) tectonic plate motions at each site. The benchmarks will be deployed from R/V Sikuliaq. Plans are underway to retrieve data from these sites in summer 2021 using the USGS waveglider. Over the next decade, repeat measurements at these and other seafloor geodetic sites in Cascadia will provide fundamental constraints on plate motions, rates of convergence, and shallow strain accumulation across one of the United States’ most hazardous fault zones.