Measurements of interface waves in the New England Mud Patch and estimation of the properties of the mud layer and underlying sand

Abstract

The New England Mud Patch is a 13,000 square kilometer area south of Martha’s Vineyard and covered by a layer of fine-grained sediments. The water depth is about 70 meters. Below the mud is a sand layer with compressional sound speed of 1745 m/s. (Bonnel, et al., 2018) Scholte and Stoneley waves were generated by the Interface Wave Sediment Profiler (iWaSP), a piezoelectric bender beam transducer which vibrates the seabed. The iWaSP was deployed in experiments in 2017 and 2022 to generate these interface waves. These waves were received at ranges of 70 to 100 meters by bottom-mounted vertical axis geophones in 2017 and Ocean Bottom Recorders (OBXs) with 3-axis geophones and a hydrophone in 2022. The speed of these interface waves is about 90% of the shear wave speed in the elastic medium. Arrivals were detected on the geophones with speeds ranging from 100 to 200 m/s for a mud thickness of about 6 meters. It is hypothesized that these waves propagated on the mud-sand interface. Based on these results, this paper will comment on the properties of the mud layer. [Sponsored by the Office of Naval Research.]