Recently, Delta Geophysics Inc. personnel performed a limited
geophysical investigation
in a residential community which displayed evidence of
sinkhole activity in a portion of the property. The
approximate size of the survey area was two acres.
Sinkholes are common where the rock below the land surface
can naturally be dissolved by ground water traversing
through them. As the rock dissolves, voids develop
underground creating a flow of water and soil into them. If
there is not enough support for the land above the voids
then a sudden collapse of the land surface can occur.
The
survey was conducted in two separate phases. The first
phase was of the survey was collecting seismic data to image
the bedrock. The second phase of the project was to collect
direct image Electrical Conductivity (EC) data around the
area of concern.
Electrical Conductivity (EC) tool is a Geoprobe mounted
instrument which detects conductivity differences in the
subsurface media. The EC tool is a vital tool for locating
potential solution zones because of the increase of
conductivity in saturated areas.
Specialized field procedures and adaptive filtering
techniques applied to the areas reduced the near-surface
influence allowing the detection of targets below the
surface. Interactive target editing and grouping tools used
by our geophysicist allowed for final data refinement. Map
making programs enabled the creation of this site map for
visualization and display during final reporting. This
final map was refined by Delta’s geophysicist using
sophisticated processing and mapping programs.
