A Multisensor Experiment to Investigate a Slippery Subduction Zone in the Cook Inlet, Alaska

Abstract The Cook Inlet segment of the Alaska-Aleutian subduction zone experiences damaging megathrust earthquakes, recurrent slow-slip events, and localized tectonic tremor. We deployed a multicomponent seismic array in the Cook Inlet vicinity to investigate the structure and geophysical properties at and near the subduction interface and understand the factors that control slip, tremor, and plate locking. This deployment combines 11 onshore broadband seismographs and a distributed acoustic sensing (DAS) campaign on offshore fiber-optic cables. Both datasets record a complementary variety of local seismic signals from earthquakes and environmental sources. The broadband network is sensitive to the teleseismic earthquake waves that can constrain deeper subduction zone structure. Noise levels are high, in part because of the basin environment and to a lesser extent because of our decision to use accessible indoor sites for deployment. The DAS data contain rich information about local noise sources, in particular, oceanographic processes within the Cook Inlet that affect land- and sea-based seismic recordings. In addition, this combined dataset provides novel perspectives of a variety of tectonic, environmental, and oceanographic signals and bridges the gap between offshore environmental forcing and onshore seismic response.