Methods for Removing Signal Noise from Helicopter Electromagnetic Survey Data

Abstract

A geophysical analysis was conducted over the abandoned T&T subsurface mines and portions of the Muddy and Roaring Creek watersheds in northeastern Preston County, West Virginia. The data were collected using helicopter-borne measurements of frequency-domain electromagnetic (FDEM) conductivity (390, 1555, 6254, 25,800, and 102,680 Hz). Noise was a significant issue in the lowest frequency EM conductivity data, especially the 390 Hz and 1555 Hz data; noise removal was accomplished by standard spatial frequency filtering, using homomorphic filters and Fourier filtering along individual flight lines. We interpret the filtered FDEM apparent conductivities and apparent resistivities as showing regions of potential mine pools and regions of contrasting groundwater conductivity related to discharge.

A trans-dimensional Bayesian Markov chain Monte Carlo algorithm for model assessment using frequency-domain electromagnetic data

“…Multifrequency electromagnetic data are commonly acquired from airborne and ground‐based systems to provide spatially continuous information about subsurface electrical resistivity variability. These data have widespread applications related to mineral exploration (Fraser 1978; Taylor 1990; Farquharson et al 2003), geological mapping (Gabriel et al 2003; Best et al 2006), groundwater (Fitterman & Deszcz‐Pan 1998; Roettger et al 2005; Lipinski et al 2008), agriculture (Allred et al 2005; Daniels et al 2008; Sams et al 2008) and environmental studies (Siemon et al 2002; Al‐Fouzan et al 2004). The EM data are often presented as maps and cross‐sections of apparent electrical resistivity (or conductivity) to highlight anomalous features of interest (Fraser 1978; Sengpiel 1988; Huang & Fraser 1996; Siemon 2001).…”

Water Management at Abandoned Flooded Underground Mines

“…Al-Fouzan et al (2004) describe an airborne mine water investigation using frequency-domain electromagnetic (FDEM) conductivity investigations. Al-Fouzan et al (2004) describe an airborne mine water investigation using frequency-domain electromagnetic (FDEM) conductivity investigations.…”

Helicopter Frequency Domain (Fdem) Surveys for Characterizing Environmental Problems Related to Mining: Observations and Conclusions From 30 Surveys

“…To a certain extent, anomalies produced by 60Hz current can be removed or isolated employing homomorphic or high pass filters. The resulting filtered component of the data may then be subtracted from the original data providing some degree of improvement (Fouzan and Harbert, 2002). Masking the data set in these areas can also be helpful, as this altogether prevents misinterpretation for the areas in question.…”