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Resistivity surveys are now also carried in areas covered by water. The surveys involve electrodes planted on the water bottom or on a streamer towed by a boat. As the water layer has a large effect on resistivity measurements, its effect must be accurately modelled. The water resistivity and depth to the bottom are usually independently measured with a conductivity meter and depth sounder. The upper part of a finite-element grid is used to model the water layer, including possible variations in the water resistivity with depth. We show the results from a 2-D survey in Stockholm with electrodes planted on the sea bottom. The sediment thickness from the inverse model agrees well with drilling results and a possible weak zone in the bedrock was detected. Surveys with floating electrodes do not follow a straight line due to water currents and a 3-D inversion approach is required. An example is shown from a survey in the Panama Canal where the data from 19 sub-parallel lines are collated into a 3-D data set. The inverse model shows a conductive bottom with weathered marine sedimentary rocks and a remnant of an old river channel filled with more resistive sands and gravels.
|Titel på värdpublikation||EAGE-GSM 2nd Asia Pacific Meeting on Near Surface Geoscience and Engineering|
|Förlag||European Association of Geoscientists and Engineers|
|Status||Published - 2019|
|Evenemang||EAGE-GSM 2nd Asia Pacific Meeting on Near Surface Geoscience and Engineering - Kuala Lumpur, Malaysia|
Varaktighet: 2019 apr. 22 → 2019 apr. 26
|Konferens||EAGE-GSM 2nd Asia Pacific Meeting on Near Surface Geoscience and Engineering|
|Period||2019/04/22 → 2019/04/26|
FingeravtryckUtforska forskningsämnen för ”The inversion of 2-D and 3-D resistivity data from surveys in aquatic areas”. Tillsammans bildar de ett unikt fingeravtryck.
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TRUST 2.1: Geoelectrical Imaging for Site Investigation for Urban Underground Infrastructure
Dahlin, T., Olsson, P., Johansson, S., Rossi, M., Sparrenbom, C., Rosqvist, H., Auken, E., Fiandaca, G., Svensson, M., Hagerberg, D., Hedblom, P. & Bastani, M.
2012/01/01 → 2018/12/31