Development and Testing of a Shielded Ocean-Bottom Seismometer to Reduce Seafloor Low-Frequency Noise

Columbia University, New York NY

Investigators

Abstract

The PI?s request funding to develop and test a shielded ocean bottom seismometer (SOBS) as a strategy for reducing the effect of current-generated tilt noise on low-frequency seismic observations made at the seafloor. The sensitive seismic sensor will be placed within a large circular steel shield that also serves as the instrument?s anchor. It is expected that this shield will reduce the current flow near the sensor reducing noise levels greatly. The establishment of fleets of large numbers of ocean bottom seismometers (OBS) capable of recording for more than a year has made it possible to study Earth structure beneath the oceans using seismic observations in much greater resolution than previously possible. The low frequency performance of these sensors is however poor compared to land sites because of very high noise levels caused by ocean currents. These high levels makes current OBS observations nearly useless for observations of Love waves, shear splitting, and receiver function analysis and can prevent the detection of shear wave arrivals from even large earthquakes at the noisier sites. Broader Impacts: One reviewer said that a better method for recording horizontal seismic energy (e.g. love waves) will benefit the entire marine (and land) geophysical community. In this regard current OBS observations are semi-limited in their ability to image Earth structure because this shear-wave data is not easily resolved. Any solution to enhance these recordings is a step toward better data resolution and interpretation.