Evaluation of MASW Data Acquired with a Hydrophone Streamer in a Shallow Marine Environment

Abstract

Seismic shear wave velocity is an important characteristic of sub-bottom materials for geotechnical and environmental characterizations in marine environments. Traditional marine shear wave velocity measurements utilize measurements within borings or data from geophones planted on the bottom. Multichannel Analysis of Surface Waves (MASW) provides a more efficient means to estimate shear wave velocity values of sub-bottom materials using a hydrophone streamer and an airgun seismic source. MASW data were acquired in a shallow marine environment and on adjacent land. Land data were acquired with a traditional spread of geophones, while the marine data were acquired with a 24-channel hydrophone streamer laid on the bottom. Phase velocity frequency spectra calculated from the data indicate that the measurements on land are repeatable with measurements underwater. Shear-wave velocity models estimated from the dispersion curves are consistent with each other and with expected geologic conditions. However, the shear-wave velocity models are strongly dependent on the model parameterization and the accuracy of the dispersion curves. Limitations include an observed narrower bandwidth of marine surface wave energy and noise resulting from towing the streamer with a boat.