The PIs are funded to use surface and body wave tomographic techniques to examine the structure of the upper mantle beneath the Juan de Fuca Plate. OBS arrays associated with the Cascadia Initiative (CI) will be used in conjunction with land arrays to investigate the evolution of the plate?mantle system, from melt production and asthenospheric structure at the spreading center to plate deformation and small-scale convection at the subduction zone, as well as asthenospheric return flow from trench to ridge. Surface and body wave data will be combined in a joint inversion, followed by waveform modeling to refine tomographic images. An additional goal is to constrain the locations and mechanisms of moderate-sized earthquakes that occur before and during the experiment. The project will partner with education and outreach efforts associated with the CI, including mentoring community college students and contributing to the Seismometers@SchoolSites program for high school students. Post-doctoral scholars and graduate students will be trained. Project data will be incorporated into undergraduate coursework and research projects. The PIs will take advantage of the UO cloud computing facility for parts of the research.