Aestus’ GeoTrax Survey™ produces high-resolution datasets that reveal subtle variations in subsurface conditions. The chosen color scale directly influences how effectively those variations are be communicated and understood.
Different electrical resistivity values correlate with changes in lithology, contaminant impacts, biodegradation zones, and structural features. Each site produces unique resistivity ranges and subsurface signatures. One color scale should not be applied across all sites because a single, universal color scale would obscure meaningful variation in many scenarios. However, using one normalized color scale for all the data sets at each individual site helps show how features trend across that specific site.
In other words, Aestus utilizes various color scales tailored for each site for better clarity and accuracy but makes sure that all of the data sets collected on a single site use the same color scale. It is important to note that, while Aestus does alter the color scale used to present the resistivity data, the underlying numerical values in the data sets are never altered.
The two graphics below show the same final ERI data set for an LNAPL site, but the color scale has been altered to highlight different electrical features.
The first image highlights electrically resistive (>250 ohm-m) portions of the electrical image. These electrical anomalies were due to dry sands.
The second image highlights electrically conductive (<10 ohm-m) portions of the electrical image. These electrical anomalies were interpreted as potentially weathered hydrocarbon impacts due to microbial activity – a hypothesis confirmed by confirmation drilling.fference between a dataset that guides confident action and one that leaves critical questions unanswered.
