1,721,002 research outputs found
ERT detectability assessment in heterogeneous and anisotropic aquifers: The choice of the starting model for forward modelling
No full textERT investigation of mud volcanoes: detection of mud fluid migration pathways from 2D and 3D synthetic modelling
No full textMud volcanoes are geological structures observed throughout the world that arise from the upwelling of deep fluids along discontinuities in the subsoil. The detection of mud fluid migration pathways can be challenging, even when using Electrical Resistivity Tomography (ERT) as detectability issues may arise from complex geological settings. This paper presents new results from 2D and 3D ERT synthetic modelling for the investigation of the shallow, internal structure of terrestrial mud volcanoes. This study revealed the internal structure of the 'Cenerone-Pineto' mud volcano (Central Italy) and provided further clues as to its internal structure. The main results of the study are: the presence of a mud chamber, which represents the last phase of mud accumulation before final emission, not located beneath the crater but laterally offset, as well as the presence of a narrow, shallow feeder channel; these findings represent evidence of a much more complex structure than one would expect. This means that the mud volcano is not supplied with mud fluids directly from below as would be the case with an uprising of deep fluid along a near-vertical open fracture and that the shallow mud fluid reservoir is not correlated to the distribution of any mud volcano observed on the surface. Findings from this study are consistent with the observed structural features already noted in ERT and seismic field data collected at the 'Cenerone-Pineto' mud volcano and may be helpful in explaining the mechanisms and processes involved in mud volcanism in similar geological settings
Fractured-karst-system investigation using ert: From shallow dissolution-enlarged fractures to deep karst intervals passing through karst conduits
No full textPSEUDO 3-D subsurface model of the main crater of the Sirente crater field (Central Italy) from seismic reflection data
No full textSubsurface structure of the proposed Sirente meteorite crater: insights from ERT synthetic modelling
No full textThe Sirente main crater is a ≈ 130 m wide, in plan view droplet-shaped depression with an elevated rim, surrounded by 30 smaller depressions. It was proposed to be of meteorite impact origin. Given the age of formation in the 3rd to 5th centuries A.D., the inferred catastrophic origin was related to the celestial sign (“Chi Rho”) said to have been seen by Emperor Constantine in 312 A.D. and suggested to have changed the course of both Roman and Christian history. However, the meteoritic origin is not yet confirmed. This paper presents new results from synthetic modelling of Electric Resistivity Tomography field data collected at the Sirente main crater which provide further clues around the controversy of its origin. This study arises from the need to validate the observed structural features which include possible upturned strata (i.e., overturning of strata below impact crater rims) and compaction-fissure-like features below and just outside the crater rim, well-developed “breccia lens”, as well as an ejecta layer, and provide key indicators for objective and quantitative interpretation of the measured resistivity pattern. The results from this study are consistent with the hypothesis of a small impact crater in a low-strength target, with a relatively shallow apparent crater and do not support other proposed mechanisms of formation such as karst, mud volcano or merely anthropogenic origin
Challenges in using ert to detect karst zones underlying thick conductive layers: Detectability, imaging quality and depth of investigation
No full textInvestigating karst aquifers: Using pseudo 3-D electrical resistivity tomography to identify major karst features
No full textEmbryonic stage sinkhole detection using electrical resistivity tomography: Comparison of different arrays
No full textReflection seismic on small ice-covered lakes and in complex geology: Investigating the sirente main crater (Central Italy)
No full text1D-4D electrical and electromagnetic methods revealing fault-controlled aquifer geometry and saline water uprising
No full textThis paper presents new results of 1D-4D electrical resistivity and electromagnetic surveys for the delineation of aquifer geometry and the detection of saline paleo-water uprising along structural discontinuities. These geophysical surveys were undertaken at the alluvial aquifer of the Oltrepò Pavese plain sector (Po Valley, Northern Italy). At the investigated test site, the alluvial aquifer is strongly conditioned by the presence of an important tectonic discontinuity whose localization and trace were better defined by this study. This fault is responsible for the sudden deepening that affects the bedrock and is also responsible for the uprising of deep, saline paleo-waters which strongly influences the chemistry of groundwater. During the campaign a variety of experimental setups were tested. This provided an ideal opportunity to cross-validate geophysical results with extensive ground truth provided by groundwater sampling and stratigraphic, electrical conductivity, temperature and redox potential logs undertaken within the wells. It also permitted an assessment of the usability of electrical and electromagnetic surveys in such a complex hydrogeological setting. Geophysical surveys revealed the presence of sharp and irregular contact between the alluvial aquifer and the underlying bedrock. This is characterized by morphological irregularities, which are likely to have been shaped either by tectonics and/or by the paleo-river's erosion. The bedrock is affected by saline water contaminations which are likely localized along structural discontinuities which represent and facilitate the flow towards the alluvial aquifer. Detailed 3D and time-lapse imaging revealed irregular-shaped shallow saline water contaminations within the alluvial aquifer, as well as temporal variability of groundwater salinity. Spatial distribution of contaminations and salinity degree are likely to be affected by different factors like the aperture of the discontinuities within the bedrock, the hydraulic conductivity of the aquifer, as well as seasonal variations in terms of fresh water recharge
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