Velocity analysis of CMP gathers acquired by an array GPR system ‘Yakumo’: results from field application to tsunami deposits
Honghua Wang 1 Hai Liu 2 5 Jie Cui 2 Xiangyun Hu 3 Motoyuki Sato 41 College of Geosciences, Guilin University of Technology, 39 Yanshan Road, Guilin 541004, China.
2 School of Civil Engineering, Guangzhou University, Guangzhou 510006, China.
3 Institute of Geophysics and Geomatics, University of Geosciences, Wuhan 430074, China.
4 Center for Northeast Asian Studies, Tohoku University, Sendai 980-8576, Japan.
5 Corresponding author. Email: liuhai8619@foxmail.com
Exploration Geophysics 49(5) 669-674 https://doi.org/10.1071/EG16134
Submitted: 8 November 2016 Accepted: 30 August 2017 Published: 26 September 2017
Abstract
This paper examines the capability of a multi-static ground penetrating radar (GPR) system ‘Yakumo’ to estimate a vertical profile of dielectric constants of stratified geological layers. Yakumo is equipped with eight transmitting and eight receiving antennas. By using Yakumo, we propose to obtain an eight-channel common mid-point (CMP) gather from the 64-channel multi-static radar dataset acquired at each point on the survey line. From each CMP gather, a vertical profile of interval velocities can be estimated by velocity spectrum analysis. By a laboratory sandbox experiment, we validate that the thickness of an 83 cm sand layer is estimated with an error of less than 4%. A field survey carried out on tsunami deposits demonstrates that our GPR method can provide the spatial distribution of layer velocities of the sedimentary structure and that the results are comparable with the geological logs at three points and a conventional common-offset GPR profile.
Key words: antenna array, common mid-point (CMP), ground penetrating radar (GPR), tsunami deposits, velocity analysis.
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