In situ compressional wave speed measurements from the New England Mud Patch using the Acoustic Coring System

In situ measurements of geoacoustic properties provide direct characterization of the seabed at near ambient conditions. The Acoustic Coring System (ACS) is a gravity corer equipped with acoustic probes that obtain in situ compressional wave (30–200 kHz) and shear wave (400–1200 Hz) measurements as the corer penetrates the seabed. During the April 2022 R/V Endeavor coring survey, the ACS was deployed at 36 locations within the New England Mud Patch (NEMP) and shelf break areas. Data from these measurements is presented to characterize the depth-dependent structure of the geoacoustic seabed properties as well as their spatial variability. The in situ measurements are interpreted in the context of stratigraphic layering measured by a seismic survey. Depth-dependent profiles of compressional speed from a subset of these deployments in the NEMP is compared to profiles previously collected at nearby locations in 2016. In situ compressional wave records from both areas are compared with ex situ sediment core measurements, including data collected from core loggers and laboratory analyses. The results obtained from the 2022 experiments are consistent with the previous and ex situ measurements, and spatially-dependent sound speed gradients are observed in and around the NEMP.