2019-02-04CDR Benjamin K. Evans, NOAACommanding OfficerNOAA Ship RainierCDR Olivia A. Hauser, NOAA2019-02-04100000Benjamin K. Evans, CDR/NOAAD002492018Mean Lower Low WaterVDatumCaliforniaPacific Hydrographic BranchIn addition to providing data for crucial nautical chart updates, this survey will also generate backscatter data, which will be used in habitat mapping and substrate analysis. Both multibeam echo sounder and backscatter data will not only serve to enhance marine navigational safety, but will also be used by sanctuary managers, planners, and researchers, aiding them in the conservation of this most precious resource. All separates are filed with the hydrographic data. Any revisions to the Descriptive Report (DR) generated during office processing are shown in bold red italic text. The processing branch maintains the DR as a field unit product, therefore, all information and recommendations within the body of the DR are considered preliminary unless otherwise noted. The final disposition of surveyed features is represented in the OCS nautical chart update products. All pertinent records for this survey, including the DR, are archived at the National Centers for Environmental Information (NCEI) and can be retrieved via http://www.ncei.noaa.gov/.meters2018-08-20Channel Islands National Marine SanctuaryEM 710Kongsberg MaritimeMBESMultibeam Acoustic BackscatterNOAA Ship Rainier2018-09-122018-10-11North American Datum 1983OPR-L397-RA-18Santa Cruz BasinProjected UTM 10Navigable AreaAll survey systems and methods utilized during this survey are described in the DAPR. No holidays were identified in the VR surface. Crosslines were not acquired on D00249 because the priority for this survey was to maximize overall MBES coverage.Data were examined for fliers using QC Tools 2 v2.7.4. After data cleaning, Detect Fliers listed 65 potential fliers. Data were investigated by the hydrographer in CARIS Subset Editor and fliers were found to be on the edge of coverage.This survey does meet charting specifications and is adequate to supersede prior data.Survey D00249 is intended as an earthquake reconnaissance survey. The data were reviewed and no DTONs were identified in this survey. This survey does meet charting specifications and the hydrographer recommends that data be retained for archival purposes and inclusion in the National Bathymetric Source database. The NOAA Ship Rainier collected and processed data to produce a variable-resolution bathymetric surface for the Pacific Hydrographic Branch. Submitted surfaces were generated using the recommended parameters for "Ranges" style variable resolution bathymetric grids as specified in HSSD 2018. Raw backscatter data was acquired as .all files logged during MBES operations and subsequently processed by personnel aboard Rainier. The .GSF files created during processing and one backscatter mosaic per vessel per frequency has been delivered with this report. Backscatter processing procedures utilized followed those detailed in the DAPR.Survey D00249 is part of OPR-L397-RA-18. The survey was requested in response to recent seismic activity approximately seven nautical miles south of Santa Cruz Island in the Santa Cruz Basin. Geologists and tsunami modelers from the US Geological Survey are interested in using the multibeam data to investigate seafloor disturbances, as submarine landslides in this region are capable of generating tsunamis.Soundings were acquired referenced to the ellipsoid and transformed to Mean Lower Low Water (MLLW) using the VDatum separation file, OPR_L397_RA_18_lgECpoly_xyNAD83-MLLW_geoid12b.csar, provided by NOAA's Hydrographic Surveys Division.