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Services: Subsurface Geophysical Surveys Shallow Underground Surveys and Non-Destructive Evaluation
Projects: Ground-Penetrating Radar Projects
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Seismic Projects Seismic Reflection & Refraction Surveys At
Large Residential Development
The
surveys were recorded with 10-foot spaced shot points and receivers to
prepare higher-resolution, 24-fold common midpoint reflection profiles.
The 1,800-foot long reflection profile shown below shows subsurface layering in the upper
500
feet. Several paralleling profiles such as this were evaluated for breaks in
subsurface layering associated with faulting. These results were
used to map the trend of several potentially active faults forming a
"pull-apart" structure beneath the former lake basin. Our
clients conducted further investigation of these seismic fault locations
using trenches and boreholes to estimate their age of last movement.
The seismic profiles and resulting geologic data were used to prepare a
final investigation of faulting for the Riverside County Building
Department.
AGI provided a "turn-key" seismic data acquisition through data evaluation program. We used our own multi-channel seismic recording equipment and completed all seismic data processing and geologic evaluation of the seismic profiles in house.
Seismic Reflection
& Refraction Surveys
AGI and Norcal Geophysical Consultants teamed together to completed seismic reflection and refraction profiles along seven 2D seismic survey lines located across an onshore area where a shaft and tunnel heading beneath the San Francisco Bay were proposed. The total lineal coverage of these 7 seismic lines was 17,000 feet (3.2 miles).
The surveys were recorded with various source and receiver configurations to prepare higher-resolution, 24 to 30-fold common midpoint reflection profiles. The reflection profiles were used to provide images of subsurface layering in the upper 700 feet. The profile below shows younger Plio-Pleistocene mudstones on lapping the older Franciscan formation. These profiles were used by our client Fugro West to map the subsurface topography of a key mudstone unit. This mudstone unit was the preferred tunneling formation.
AGI supervised the seismic data recording operations and supplied its own 120-channel seismic recording system. AGI also completed all data processing of the seismic reflection profiles and worked with Fugro West to integrate these profiles into their Kingdom interpretation work station.
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