Collaborative Research: Broadband Seismic Measurement on the Deep Ocean Floor: A Pilot Experiment

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9523541 Orcutt This team of investigators from Woods Hole Oceanographic Institution (Massachusetts), Scripps Institution of Oceanography (University of California, San Diego, California) and Rosenstiel School of Marine and Atmospheric Sciences (University of Miami, Florida) will jointly develop and test three types of deep-ocean seismometers as a pilot experiment for a set of ocean sensors to expand the existing land-based "global" seismic network to one which has truly global coverage. Global seismic coverage with broadband seismometers provides a capability to accurately define the interior structure of the earth with resolution presently not possible, and it provides a capability to significantly improve warnings for tsunamis. The instruments to be used in the present project are all "broadband" sensors, and will be deployed respectively 1) lying on the seafloor, 2) buried slightly within marine sediments, and 3) within an existing seafloor drill hole. All deployments will be carried out for the same 3-month period in early 1997. The borehole deployment will use a specially developed system (Scripps Institution) to place the instrument in the borehole; the buried sensors will be emplaced with a system developed at University of Miami. Tests will take place near Hawaii, and results of all three systems will be compared with a permanent land seismometer on the island of Oahu as well as with each other. This project is jointly supported by Ocean Sciences and Earth Sciences Divisions of the Geosciences Directorate at NSF, and follows earlier development and testing programs of component instruments. It is expected that this test will allow decisions to be made about what types of deployments (surface, buried or in drillholes) will be optimum for future "ocean seismic network" deployments. ***