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20 pages, 8262 KB

Open AccessArticle

Seismic Measurements Using Distributed Acoustic Sensing (DAS) for Underwater Soft Sediment Characterization: Insights from Laboratory- and Field-Scale Measurements

by Edwin Obando Hernandez, Matteo Rossi, Roeland Nieboer, Manos Pefkos, Wiebe de Boer and Pieter Doornenbal

Sensors 2025, 25(23), 7234; https://doi.org/10.3390/s25237234 - 27 Nov 2025

Cited by 1 | Viewed by 1494

Abstract

Scholte wave surveys were conducted at both the laboratory and field scales to evaluate the reliability of distributed acoustic sensing (DAS) with a fiber-optic cable resting on top of unconsolidated sedimentary deposits to determine the distribution of S-wave velocity underneath. Laboratory measurements performed in a controlled environment at the Deltares Laboratory facility demonstrated that DAS retrieves low- and high-frequency energy associated with Scholte and guided waves. The recorded DAS signals provided consistent Scholte wave signals, which depicted coherent phase velocity energy that was used to accurately depict S-wave velocity layering. We observed the presence of guided waves at higher frequencies, which appeared to be enhanced as the source position was moved away from the fiber-optic cable. A field survey was carried out using a linear set-up in a shallow lake, where a fiber-optic cable was placed on top of a sediment layer with a thickness of 5–10 m. The results from DAS were validated using standard hydrophone measurements performed simultaneously. The 2D S-wave velocity cross-section retrieved by DAS appeared to be in good agreement with the results obtained from hydrophone measurements, especially when detecting the main velocity transition occurring at a 7–10 m depth from the free surface. Full article

(This article belongs to the Special Issue Distributed Acoustic Sensing and Applications)

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15 pages, 2897 KB

Open AccessArticle

Laser-Generated Scholte Waves in Floating Microparticles

by Abhishek Ranjan, Azeem Ahmad, Balpreet Singh Ahluwalia and Frank Melandsø

Sensors 2023, 23(4), 1776; https://doi.org/10.3390/s23041776 - 4 Feb 2023

Cited by 2 | Viewed by 2621

Abstract

This study aims to demonstrate the generation and detection of Scholte waves inside polystyrene microparticles. This was proven using both experimental analysis and COMSOL simulation. Microspheres of different sizes were excited optically with a pulsed laser (532 nm), and the acoustic signals were detected using a transducer (40 MHz). On analyzing the laser-generated ultrasound signals, the results obtained experimentally and from COMSOL are in close agreement both in the time and frequency domain. A simplified analysis of Scholte wave generation by laser irradiation for homogeneous, isotropic microspheres is presented. The theoretical wave velocity of the Scholte wave was calculated and found close to our experimental results. A representation of pressure wave motion showing the Scholte wave generation is presented at different times. Full article

(This article belongs to the Section Optical Sensors)

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14 pages, 5303 KB

Open AccessArticle

Study on a Detection Technique for Scholte Waves at the Seafloor

by Minshuai Liang, Liang Wang, Gaokun Yu, Yun Ren and Linhui Peng

Sensors 2022, 22(14), 5344; https://doi.org/10.3390/s22145344 - 18 Jul 2022

Cited by 5 | Viewed by 3241

Abstract

Scholte waves at the seafloor have significant potential for underwater detection and communication, so a study about detecting Scholte waves is very meaningful in practice. In this paper, the detection of Scholte waves at the seafloor is researched theoretically and experimentally. Acoustic models with the multilayer elastic bottom are established according to the ocean environment, and a tank experiment is designed and carried out to detect Scholte waves. Different from detecting Scholte waves in the seismic wavefield, a technique for detecting Scholte waves in the sound pressure field is proposed in this paper. The experimental results show that the proposed technique can detect Scholte waves effectively, and there are no problems such as seabed coupling and the effect of wave speeds. Furthermore, the results also show that this detection technique is still effective in conditions with a sediment layer. The existence of sediment layers changes the acoustic field conditions and affects the excitation of Scholte waves. Full article

(This article belongs to the Special Issue Detection and Feature Extraction in Acoustic Sensor Signals)

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