Marine electrical resistivity tomography for shipwreck detection in very shallow water: a case study from Agropoli (Salerno, southern Italy)

Passaro, Salvatore

doi:10.1016/j.jas.2010.03.004

Cited by 41 publications

(27 citation statements)

References 35 publications

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“…In order to estimate the exact v(z p , t) from the measurements under these extreme noise conditions, suppose that at time t, we sample the potential field s times on each active electrode, for example, {u (1) (z p , t), . .…”

Section: Filtering the Datamentioning

confidence: 99%

“…The measurements of electric potential are sensitive to the depth-averaged bulk conductivity, as defined in (1). The proposed framework is thus appropriate for localizing depthinvariant inhomogeneities of small diameter and small discrete inclusions situated near the surface as long as their conductivity value provides an adequate contrast to the bulk conductivity of the background medium.…”

Section: A Model Limitations and Extensionsmentioning

confidence: 99%

“…As the seawater is conductive to electric current, the sensitivity of these measurements to the electrical conductivity spans a considerable distance, both horizontally and vertically, subject to the magnitude of the applied currents. It is thus unsurprising that marine electrical sensing has found numerous applications in geophysical investigations, including maritime archaeology [1], environmental surveys [2], forensic investigations [3], and hydrocarbon exploration [4]. In these applications, one typically utilizes these voltage measurements in order to image the electrical properties of the water column and the subseabed sediment.…”

Section: Introductionmentioning

confidence: 99%

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Marine Electrical Sensing for Detecting Small Inhomogeneities

Polydorides

Delbary

2015

IEEE Trans. Geosci. Remote Sensing

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We consider towed electrical sensing for detecting and localizing small inhomogeneities in the marine environment. Assuming the domain to be homogeneous apart from a few dispersed inclusions, the low-frequency electrical measurements can be modeled using a single-layer potential formulation for a source function defined at the boundaries of the inclusions. A key component of these measurements is the potential induced by the polarization of the inclusions, which at the far field can be shown to be equivalent to the potential of dipole sources centered at the inclusions. Under this approximation, we formulate an inverse problem for localizing the inclusions and then enforce some regularization in the form of an a priori assumption on the shape of the inclusions. In this context, solving the inverse problem requires tracing some coordinates where the polarization potential at the current injecting electrodes becomes zero since these define a set of lines intersecting at the center of the targeted inclusions. This methodology is implemented by a simple algorithm, whose computational complexity mounts to solving a small number of low-dimensional linear systems. Analysis indicates fair robustness of the algorithm to measurement noise and model inaccuracies, and this is also supported by numerical simulation experiments.Index Terms-Electric dipole approximation, polarizationinduced potential, single-layer potential formulation, towed electrical survey.

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Section: Filtering the Datamentioning

confidence: 99%

Section: A Model Limitations and Extensionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Marine Electrical Sensing for Detecting Small Inhomogeneities

Polydorides

Delbary

2015

IEEE Trans. Geosci. Remote Sensing

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“…Passaro [19] managed to outline the shape of a military shipwreck as low calculated resistivity values from a towed floating mobile configuration. A comprehensive feasibility study on the efficiency of ERT in reconstructing submerged archaeological relics in shallow seawater environments, based on extensive numerical models verified by subsequent field experimentation, is given by Simyrdanis et al [20].…”

Section: Introductionmentioning

confidence: 99%

“…The vast majority of marine ERT applications involve the implementation of 2-D measurement and processing approaches for the characterization of the sub-bottom stratigraphy. Efforts toward the direction of 3-D underwater resistivity mapping have been limited in the collection of multiple dynamic ERT lines in a floating mode and subsequent analysis though a quasi-3D approach [19]. This work goes a step further in the investigation of a submerged archaeological site through the employment of a true 3-D imaging resistivity survey in terms of data acquisition and processing, constraining simultaneously the modeling and inversion procedure with the thickness and salinity of the water layer.…”

Section: Introductionmentioning

confidence: 99%

Shallow Off-Shore Archaeological Prospection with 3-D Electrical Resistivity Tomography: The Case of Olous (Modern Elounda), Greece

2016

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Abstract:It is well known that nowadays as well as in the past the vast majority of human habitation and activities are mainly concentrated in littoral areas. Thus the increased attention to coastal zone management contributed to the development and implementation of shallow-water mapping approaches for capturing current environmental conditions. During the last decade, geophysical imaging techniques like electrical resistivity tomography (ERT) have been used in mapping onshore buried antiquities in a non-destructive manner, contributing to cultural heritage management. Despite its increased implementation in mapping on-shore buried archaeological remains, ERT has minimal to non-existent employment for the understanding of the past dynamics in littoral and shallow off-shore marine environments. This work presents the results of an extensive ERT survey in investigating part of the Hellenistic to Byzantine submerged archaeological site of Olous, located on the north-eastern coast of Crete, Greece. A marine area of 7100 m 2 was covered with 178 densely spaced ERT lines having a cumulative length of 8.3 km. A combination of submerged static and moving survey modes were used to document potential buried and submerged structures. The acquired data from the marine environment were processed with two-dimensional and three-dimensional inversion algorithms. A real time kinematic global navigation satellite system was used to map the visible submerged walls and compile the bathymetry model of the bay. The adaptation of ERT in reconstructing the underwater archaeological remains in a shallow marine environment presented specific methodological and processing challenges. The in situ experience from the archaeological site of Olous showed that ERT provided a robust method for mapping the submerged archaeological structures related to the ancient built environment (walls, buildings, roads), signifying at the same time the vertical stratigraphy of the submerged sediments. The inherent limitation of employing ERT in a conductive environment is counterbalanced by the incorporation of precise knowledge for the conductivity and bathymetry of the saline water in the modelling and inversion procedure. Although the methodology definitely needs further refinement, the overall outcomes of this work underline the potential of ERT imaging being integrated into wider shallow marine projects for the mapping of archaeological sites in similar environmental regimes.

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Imaging a medieval shipwreck with the new PingPong 3D marine reflection seismic system

Wilken

Wunderlich

Hollmann

et al. 2019

Archaeological Prospection

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We present a new three-dimensional (3D) marine seismic data acquisition system, named PingPong, developed for archaeological prospection in shallow water.Prospection targets for the system are ancient harbour sites and sedimented remains of shipwrecks. The prospection of such targets often means working at the transition from land to water, in areas of only a few meters of water depth and hardly accessible waters. An acquisition system for such environments needs to meet specific demands, especially low draught and marginal weight besides the requirements of archaeological prospection, meaning decimetre resolution and 3D imaging capabilities, together with fast multichannel acquisition to be able to cover large areas. We explain the properties of the PingPong system and show its imaging capabilities using the case study of a sedimented medieval shipwreck. The study area is located at the innermost part of the Baltic fjord Schlei, Germany. In 2014, divers found a wreck in this area, mostly covered by mud. Findings and two timbers, dated by dendrochronology, indicated that the wreck is a Scandinavian transport ship dating to the middle of the twelfth century and related to Schleswig, which is located 2 km northwest of the study area.We show that the PingPong system is able to image the major remains of the wooden wreck at the seafloor and underneath. The acquired seismic datacube has a resolution of 0.15 m. It shows a number of distinct reflections that can clearly be assigned to the shipwreck, helping to understand the overall condition of the wreck. The reflections originate from one half the ship's hull, which is tilted to the side. The reflections concentrate in the first metre below the seafloor and correlate well with the results from the diving prospection.

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Marine electrical resistivity tomography for shipwreck detection in very shallow water: a case study from Agropoli (Salerno, southern Italy)

Cited by 41 publications

References 35 publications

Marine Electrical Sensing for Detecting Small Inhomogeneities

Marine Electrical Sensing for Detecting Small Inhomogeneities

Shallow Off-Shore Archaeological Prospection with 3-D Electrical Resistivity Tomography: The Case of Olous (Modern Elounda), Greece

Imaging a medieval shipwreck with the new PingPong 3D marine reflection seismic system

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