The two dominating difficulties of any geophysical measurement in the urban setting are as follows : ( 1) the area available for measurement is small, so the geoelectric layout length is also small; (2) the noise level is high, and the noise reduces the maximum depth from which any subsurface target can be detected. From the results of two-dimensional numerical model computations assuming multielectrode (electrical resistivity tomography) measurements, we determined the depth of detectability values ( i.e. maximum depth values at which still useful information about a given inhomogeneity is obtained at a given noise level). We conducted detectability studies in detail for six different geoelectric arrays, assuming different noise levels. The depth of detectability is both array-and model-dependent, as it has been found. Therefore, it is recommended to pick an array in a field study that has the greatest possible depth of detectability values for the given model. At the noise level given. If there is no a priori assumption about the subsurface model, we suggest either the pole-dipole (P-DP) array or the dipole axial (DP-ax) array as a default option, because they have the largest detectability values for most models we have studied. A double increase in the level of noise can lead to a decrease of approximately two in the detectability depth itself.
Author (s) Details
Sándor Szalai
1CSFK GGI, H-9401 Sopron POB 5, Hungary and Department of Geophysics, University of Miskolc, H-3515 MiskolcEgyetemváros, Hungary.
Mátyás Krisztián Baracza
3Research Institute of Applied Earth Sciences, University of Miskolc, H-3515 Miskolc-Egyetemváros, Hungary.
Attila Novák
CSFK GGI, H-9401 Sopron POB 5, Hungary.
László Szarka
CSFK GGI, H-9401 Sopron POB 5, Hungary.
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