Anomalous reflection from a two-layered marine sediment

Area of Science:

• Geophysics
• Acoustics
• Marine Sedimentology

Background:

• Marine sediments often feature layered structures with varying acoustic properties.
• Understanding acoustic reflection is crucial for geophysical surveying and sub-seafloor characterization.

Purpose of the Study:

• To theoretically investigate acoustic reflection from a two-layered marine sediment.
• To analyze the influence of different sound speed profiles within the mud layer on reflection characteristics.
• To explore the potential of acoustic glint for inferring sediment properties.

Main Methods:

• Modeling acoustic reflection coefficient for a marine sediment layer.
• Considering three sound speed profiles: uniform, linear, and inverse-square.
• Analyzing the background reflection and acoustic glint phenomena.

Main Results:

• A background reflection component shows weak sensitivity to profile gradient, frequency, and depth.
• Non-uniform sound speed profiles (linear, inverse-square) produce narrow spikes of total reflection (acoustic glint).
• Acoustic glint's angular distribution is sensitive to frequency and depth, mildly to gradient.

Conclusions:

• Acoustic glint patterns act as unique "fingerprints" for marine mud layers.
• Detecting acoustic glint at multiple frequencies could allow inference of mud layer depth and sound speed gradient.
• This method offers a sensitive approach for sub-seafloor property determination.