Characterization of seismic noise at two shallow water sites in the United States East Coast

Abstract

This study analyzes the ambient seismic data recorded on geophones and ocean bottom seismometers (OBXs) at two shallow water (water depth ~ 26 m) locations in the US East Coast off Block Island, Rhode Island and Maryland, respectively. The Block Island site was the location of the first offshore wind farm in the United States. Data were collected at this site during three different deployments in 2015, 2016 and 2017. Data collected on a 3-axis geophone will be discussed in this study. This sensor package included a 3-axis geophone and a colocated hydrophone. This 3-axis geophone measured the particle motion (particle velocity) in three mutually perpendicular directions along with acoustic pressure. The same sensor package was deployed recently ten miles east of Ocean City, Maryland. During this deployment, in addition to the geophone package, four Ocean Bottom Recorders (OBXs) were also deployed as a line array. A number of weather events including hurricanes Dorian, Humberto, Lorenzo and tropical storm Karen passed through the Maryland site during the deployment. This study will discuss the data that was collected to identify the potential signatures of these storms. Data from these two sites will be compared and sources of seismic noise and their frequency bands will be identified. The seismic data will be compared with standard low- and high-noise models.