Seismic Refraction and Electromagnetic Surveys at Fort Detrick, Maryland
ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS GEOTECHNICAL LAB
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A geophysical investigation was conducted to determine the depth of bedrock and to delineate a suspect geologic fault with a northwest-southeast orientation that runs through the center of Area B, Fort Detrick, Maryland. Previous geologic investigations indicate Cambrian limestones and Triassic shales southwest and northwest of the fault, respectively. Two seismic refraction and two EM survey lines were run at Area B to determine the depth to top of rock and to find evidence of the suspected fault. The seismic refraction method was used to obtain velocity cross sections along each of the 1440-ft long survey lines. The velocity cross sections indicated three velocity zones. The two uppermost layers are interpreted as corresponding to dry unconsolidated materials. The third and deepest layer, ranging in depth between approximately 9 and-49 ft, and having velocities ranging between 13,050 and 16,100 fps is presumed to correspond to bedrock. No clear evidence of a fault was interpreted from the seismic refraction surveys. Two EM survey lines, with lengths of 925 and 1865 ft, were run at the site to determine the location of the geologic fault. The maximum depth of investigation for these surveys was approximately 100 ft. In general, the Electromagnetics, Geophysics, Geophysical surveys, Seismic refraction.
- Hydrology, Limnology and Potamology
- Water Pollution and Control