2018-12-29_REVISION - C1981041 - Laserfiche WebLink

Home Browse Search

In addition to the survey performed over the primary area of concern, an additional 1 -acre survey was performed over a plot of land approximately 0.7 miles to the south-southwest of the Fontanari Track 70 site, known to be unaffected by subterranean mining activities (Figure 5). The survey employed the same parameters as the primary survey, and is intended to be used as a control experiment to validate the results of the primary survey. Figure 5. Overview map of the primary survey area (in white), and the location of the control survey plot (red star), from Google Earth Images. Data Processing Raw EM -31 data were converted to tabular data files using TrackMaker 31, version 1.65, by Geomar Software Inc. Further data processing and gridding of the FDEM data was performed using Geosoft Oasis momaj (Geosoft), version 8.5.1, a processing and data visualization software suite used for analysis of geophysical data sets. Data were corrected for any drift in the background readings over time, which can be caused by temperature variation during operation. Following the corrections, Geosoft was used to grid the GPS -registered quadrature and in-phase component responses using the minimum curvature method. The grids were then exported as plan view map images showing both components of the electromagnetic response for each instrument and frequency combination. The in- phase component of the EM -31 did not indicate any anomalous condition, and as such any further processing focused on the quadrature component most sensitive to the geophysical conditions of interest (i.e., electrical conductivity). The conductivity map was further filtered in an image processing suite called hnageJ, developed by the National Institutes of Health (NIH). A terrain mask was generated using a rolling ball algorithm (Figure 6), adopted from a technique developed for medial imaging processing (Rashed, 2016). Project No. 6422A 5 Geophysical Report