Calibration and Filtering Strategies for Frequency Domain Electromagnetic Data

Minsley, Burke J.; Smith, Bruce D.; Hammack, Richard; Sams, James I.; Veloski, Garret

doi:10.3997/2214-4609-pdb.175.sageep022

Cited by 7 publications

(11 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In each investigation line, we collected two datasets, keeping an average height of the device as constant as possible to 1 m ( Figure 4 ), one using a horizontal orientation of the coils ( HCP ) and the other with a vertical orientation ( VCP ). We acquired several hundreds of measurement points for each transect, using a sampling step of 0.5 s, collecting the survey a few times to avoid the possible air temperature drift [ 71 , 72 ]. Scattered values, local anomalies or negative values of conductivity may be recorded due to FDEM electronic instrumental drift.…”

Section: Methodsmentioning

confidence: 99%

Electrical and Electromagnetic Geophysical Prospecting for the Monitoring of Rock Glaciers in the Dolomites, Northeast Italy

Pavoni

Sirch

Boaga

2021

Sensors

View full text Add to dashboard Cite

The monitoring of rock glaciers plays a relevant role in relation to natural hazards in high mountain environments. Due to the climate warming, mountain permafrost is thawing, and its degradation is influencing the triggering and the evolvement of processes such as rockfalls, landslides, debris flows and floods. Therefore, the study and monitoring of these periglacial forms have both a scientific and economic importance. We tested electrical and electromagnetic measurements along the same investigation lines, in two different sites of the Dolomites area (Northeast Italy). Electrical prospecting exploits the high resistivity contrast between frozen and non-frozen debris. However, these measurements have high logistic demands, considering the complex rock glaciers surface and the need of ground galvanic contact. For this reason, we tried to compare electrical measurements with electromagnetic contactless ones, that theoretically can be used to define the distribution of electrical resistivity in the first subsoil in a quicker and easier way. The obtained results show that the joint use of the two methods allows us to characterize a rock glacier subsoil with good confidence. Finally, the advantages and disadvantages of both the techniques are discussed.

show abstract

Section: Methodsmentioning

confidence: 99%

Electrical and Electromagnetic Geophysical Prospecting for the Monitoring of Rock Glaciers in the Dolomites, Northeast Italy

Pavoni

Sirch

Boaga

2021

Sensors

View full text Add to dashboard Cite

show abstract

“…Large-scale EMI data are rarely normally distributed [Minsley et al, 2012], although this is required for most filter strategies. To overcome this limitation, we developed a novel histogram-filter that identifies and excludes outliers.…”

Section: Processing and Filteringmentioning

confidence: 99%

“…However, drilling at numerous sampling locations may be required. Another calibration approach relies on a linear regression between predicted apparent electrical conductivities obtained from a Maxwell-based full-solution EM forward model using inverted ERT data as input and the ECa values recorded with EMI along the same transect [Lavou e et al, 2010;Minsley et al, 2012]. Sudduth et al [2013] inverted calibrated EMI data for two-layer and three-layer subsurface models using the linear local sensitivity forward model of McNeill [1980] that estimates ECa under the low induction number (LIN) approximation, i.e., the induction number has to be much smaller than unity.…”

Section: Introductionmentioning

confidence: 99%

Three‐dimensional imaging of subsurface structural patterns using quantitative large‐scale multiconfiguration electromagnetic induction data

Hebel

Rudolph

Mester

et al. 2014

Water Resources Research

117

102

View full text Add to dashboard Cite

Electromagnetic induction (EMI) systems measure the soil apparent electrical conductivity (ECa), which is related to the soil water content, texture, and salinity changes. Large-scale EMI measurements often show relevant areal ECa patterns, but only few researchers have attempted to resolve vertical changes in electrical conductivity that in principle can be obtained using multiconfiguration EMI devices. In this work, we show that EMI measurements can be used to determine the lateral and vertical distribution of the electrical conductivity at the field scale and beyond. Processed ECa data for six coil configurations measured at the Selhausen (Germany) test site were calibrated using inverted electrical resistivity tomography (ERT) data from a short transect with a high ECa range, and regridded using a nearest neighbor interpolation. The quantitative ECa data at each grid node were inverted using a novel three-layer inversion that uses the shuffled complex evolution (SCE) optimization and a Maxwell-based electromagnetic forward model. The obtained 1-D results were stitched together to form a 3-D subsurface electrical conductivity model that showed smoothly varying electrical conductivities and layer thicknesses, indicating the stability of the inversion. The obtained electrical conductivity distributions were validated with low-resolution grain size distribution maps and two 120 m long ERT transects that confirmed the obtained lateral and vertical large-scale electrical conductivity patterns. Observed differences in the EMI and ERT inversion results were attributed to differences in soil water content between acquisition days. These findings indicate that EMI inversions can be used to infer hydrologically active layers.

show abstract

“…A similar approach has been presented by Deszcz-Pan and others (1998), Reid and Bishop (2004), Brodie and Sambridge (2006) and Minsley and others (2012). Because of systematic errors in our instrument, we corrected our data according to Eqns (1) and (2) to get reliable results.…”

Section: Methodsmentioning

confidence: 96%

Towards an estimation of sub-sea-ice platelet-layer volume with multi-frequency electromagnetic induction sounding

et al. 2015

View full text Add to dashboard Cite

ABSTRACT. Ice-platelet clusters modify the heat and mass balance of sea ice near Antarctic ice shelves and provide a unique habitat for ice-associated organisms. The amount and distribution of these ice crystals below the solid sea ice provide insight into melt rates and circulation regimes in the ice-shelf cavities, which are difficult to observe directly. However, little is known about the circum-Antarctic volume of the sub-sea-ice platelet layer, because observations have mostly been limited to point measurements. In this study, we present a new application of multi-frequency electromagnetic (EM) induction sounding to quantify platelet-layer properties. Combining in situ data with the theoretical response yields a bulk platelet-layer conductivity of 1154 � 271 mS m -1 and ice-volume fractions of 0.29-0.43. Calibration routines and uncertainties are discussed in detail to facilitate future studies. Our results suggest that multi-frequency EM induction sounding is a promising method to efficiently map platelet-layer volume on a larger scale than has previously been feasible.

show abstract

Calibration and Filtering Strategies for Frequency Domain Electromagnetic Data

Cited by 7 publications

References 0 publications

Electrical and Electromagnetic Geophysical Prospecting for the Monitoring of Rock Glaciers in the Dolomites, Northeast Italy

Electrical and Electromagnetic Geophysical Prospecting for the Monitoring of Rock Glaciers in the Dolomites, Northeast Italy

Three‐dimensional imaging of subsurface structural patterns using quantitative large‐scale multiconfiguration electromagnetic induction data

Towards an estimation of sub-sea-ice platelet-layer volume with multi-frequency electromagnetic induction sounding

Contact Info

Product

Resources

About