Apparent resistivity and spectral induced polarization in the submarine environment

Abstract

Relatively few investigations have employed electrical methods in the submarine environment, which may be promising for mineral deposits or threatened by environmental problems. We have measured the electric field using both disk and bar electrodes in the sea water at three different levels: sea surface, seven meters deep, and sea bottom at a depth of ten meters, employing a 2 m spacing dipole-dipole array with 7 array spacings of investigation, and 13 values of frequencies at steps of (2 N hertz, N = -2, -1, 0, 1, 2,.....10). The measurement allowed the analysis of the electric field as a function of frequency and spacing, and of the spectral induced polarization. Modelling and interpretation of the apparent resistivity yielded a good fit with previous drilling data. Analysis of the spectrum of the complex apparent resistivity and the comparison with equivalent circuits, provided information about the grain size, the mineral composition and the major induced polarization phenomenon occurring below the sea. Therefore the result of the present research show the feasibility of measuring the variation of seawater resistivity in situ, as well as the resistivity of sea bottom sediments.

Electrical resistivity tomography mapping of beachrocks: application to the island of Thassos (N. Greece)

“…The advent of automated resistivity meters combined with the developments of advanced interpretation (inversion) algorithms Barker 1995, 1996) allow the rapid acquisition of accurate images of the subsurface resistivity and render ERT one of the most important near surface geophysical techniques. Simple modification of instrumentation allow the application of ERT into addressing environmental and engineering problems related to marine environments as several recent applications suggest (Zhou et al 2000;Drahor et al 2006;Yang et al 2002;De Souza and Sampaio 2001).…”

ERT and GPR Prospecting Applied to Unsaturated and Subwater Analogue Archaeological Site in a Full Scale Laboratory

“…In general, surveys in water-covered areas include conventional surveys using a multi-electrode resistivity system where part of the survey line crosses a river or a lake, and surveys conducted entirely within a water-covered environment. In applications in seas and rivers, this method has been performed both with fixed electrodes placed on the water surface or on the seabed and riverbed [23][24][25][26][27][28][29] or by dragging the electric cable on the water surface with the aid of ships or boats [30,31]. In the first case, usually, the cable is weighted in order to allow direct contact with the marine sediments.…”

Complex Resistivity Dispersion Characteristics of Water‐Bearing Coal Based on Double Cole‐Cole Model

“…Compared with other methods, it can obtain more electrical parameters and geoelectric information [11]. e technology has been widely used in many fields such as geological exploration, soil environmental assessment [12], and ocean exploration [13]. Under the action of additional electric field (primary electric field), rocks or ores due to electrochemical action will produce induced polarization (secondary electric field), and the interval where the secondary electric field lags behind the primary electric one is called relaxation time, which can be obtained by complex resistivity parameters.…”