Bathymetric Survey: Completion of Coverage of the Cascadia Subduction Zone in Support of the Cascadia Initiative OBS Array Deployment

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As part of the 2009 ARRA (American Recovery and Reinvestment Act) spending, NSF?s Earth Sciences (EAR) and Ocean Sciences (OCE) divisions each received $5M in facility-related investment. The funds were targeted toward the creation of an Amphibious Array Facility to support EarthScope and MARGINS science objectives. The first of these studies will take place in Cascadia (offshore northern California, Oregon, Washington and southern British Columbia), where there is significant risk of a major subduction zone, ?megathrust? earthquake that will affect population centers including Vancouver, Seattle and Portland. With the primary aim of improving our understanding of seismicity and seismic risk in this region, 60 or more Ocean Bottom Seismographs (OBS) will be deployed across the region over a period of four years beginning in the summer of 2011. The recent earthquake and tsunami in northern Japan, a setting not unlike Cascadia, provide fresh impetus for this study. Good bathymetric data are essential for choosing OBS station locations. Because many of the deployments occur in and near active canyon systems and very seismically active areas, site selection will be difficult, and good bathymetric data are required to minimize the loss of instruments. The proposed cruise will fill in poor bathymetric coverage in Cascadia, particularly along the Washington and Canadian margins. In addition to its obvious contribution to the overall objective of the Cascadia Initiative, broader impacts of this effort include improvements in regional bathymetric coverage that will significantly improve our understanding of the Cascadia subduction margin, and have implications for seismic hazards in the western U.S. Additionally, the project will provide training and support for a graduate student.