In situ measurements of compressional and shear wave speed and compressional wave attenuation using the acoustic coring system

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2023-12

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Abstract

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 obtains 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 New England Shelf Break areas. Data from these experiments were analyzed to characterize the depth-dependent structure of the seabed geoacoustic 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 wave speed from a subset of these deployments in the NEMP are 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. Additionally, novel in situ shear wave speed measurements from the NEMP and surrounding areas are introduced.

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