Development and Testing of Pressure Gradient Sensors to Improve Shallow Seafloor Seismic Observations

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The PIs request funding to develop and test on current shielded OBSs orthogonal pairs of horizontal pressure gradient (OPG) sensors. These sensors will be based on the sensor technology originally developed by one of us (Webb) for the differential pressure gauge (DPG) systems currently used on the majority of the US OBS fleet. Theory suggests that these pressure gradient observations should be proportional to the wave deformation loading noise and thus can be used to predict and remove the wave loading noise from the horizontal components. Combining data from a current shielded OBS with data from APG and OPGs sensors may enable broadband seismic observations on the shallow seafloor with noise levels comparable to many land sites greatly improving OBS data for studying the Earth. This project should greatly enhance the capabilities of ocean bottom seismometers deployed in shallow water for studying the seismicity and structure of continental margins crucial to understanding the Earth and the Earth?s seismic hazard.Broader Impacts: This instrument development will be a tremendous asset for future relatively shallow water deployments of broadband instruments as it will improve the quality of the data significantly and will make the horizontal component data really useable for a wide range of structural studies. A significant reduction of noise due to waves would benefit a host of OBS programs planned or anticipated in Cascadia, Alaska, New Zealand and elsewhere. Because all of these regions are potential sites of great earthquakes and tsunamis, there are also high societal benefits in improved OBS data.