Three-dimensional resistivity characterization of a coastal area: Application of Grounded Electrical-Source Airborne Transient Electromagnetic (GREATEM) survey data from Kujukuri Beach, Japan

• Published in: Journal of applied geophysics Vol. 99; pp. 1 - 11
• Main Authors: Abd Allah, Sabry, Mogi, Toru, Ito, Hisatoshi, Jomori, Akira, Yuuki, Youichi, Fomenko, Elena, Kiho, Kenzo, Kaieda, Hideshi, Suzuki, Koichi, Tsukuda, Kazuhiro
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2013
• Subjects: 3D resistivity modeling; Airborne electromagnetics; Austenitic stainless steels; Coastal areas; Coordinate transformations; Data processing; Electrical resistivity; Geological surveys; Grounded Electrical-Source Airborne Transient Electromagnetic (GREATEM) survey; Stacking; Three dimensional; INW, Japan, Honshu, Chiba Prefect., Boso Peninsula, Kujukuri; INW, Japan; 3D resistivity modeling; Grounded Electrical-Source Airborne Transient Electromagnetic (GREATEM) survey; Coastal areas; Airborne electromagnetics
• ISSN: 0926-9851; 1879-1859
• DOI: 10.1016/j.jappgeo.2013.09.011

An airborne electromagnetic (AEM) survey using the Grounded Electrical-Source Airborne Transient Electromagnetic (GREATEM) system was conducted over the Kujukuri coastal plain in southeast Japan to assess the system's ability to accurately describe the geological structure beneath shallow seawater. To obtain high-quality data with an optimized signal-to-noise ratio, a series of data processing techniques were used to obtain the final transient response curves from the field survey data. These steps included movement correction, coordinate transformation, the removal of local noise, data stacking, and signal portion extraction. We performed numerical forward modeling to generate a three-dimensional (3D) resistivity structure model from the GREATEM data. This model was developed from an initial one-dimensional (1D) resistivity structure that was also inverted from the GREATEM field survey data. We modified a 3D electromagnetic forward-modeling scheme based on a finite-difference staggered-grid method and used it to calculate the response of the 3D resistivity model along each survey line. We verified the model by examining the fit of the magnetic-transient responses between field data and the 3D forward-model computed data, the latter of which were convolved with the measured system responses of the corresponding data set. The inverted 3D resistivity structures showed that the GREATEM system has the capability to map resistivity structures as far as 800m offshore and as deep as 300–350m underground in coastal areas of relatively shallow seawater depth (5–10m). •We examined the applicability of the GREATEM method to coastal area research.•We made a 3D resistivity model to account for lateral resistivity variation.•The merits of the 3D resistivity models over 1D models have been reported.