High Resolution Seismic Surveys at U.S. Marine Corps Air Station, Cherry Point, North Carolina
by
Richard D. Miller and Jianghai Xia
technical support by
Joe M. Anderson and David R. Laflen

Abstract
Shallow seismic reflection techniques were successful in delineating stratigraphic units and bedding geometries significant to the hydrologic modeling of sediments less than 60 m deep at the U.S. Marine Corps Air Station at Cherry Point, North Carolina. Discontinuous confining units beneath an industrialized portion of this major aircraft overhaul facility were thought to be due the erosion by a river that had cut through this area. Shallow seismic reflection techniques provided images of alternating sand and clay sequences with average thicknesses on the order of 6 to 9 m. The data have a dominant frequency of about 200 Hz, providing a minimum vertical bed resolution of about 2 m. Correlation of the CDP stacked seismic section with the drillhole-defined lithology was enhanced by incorporating electric logs and VSPs acquired in three strategically placed monitor wells. Some processed VSPs have interpretable reflections from within the upper 70 m that are consistent with the geologic section as inferred from drilling and electric logs. Subtle stratigraphic contacts, such as shell layers within sand, may be interpretable in some places on the CDP stacked sections. The land seismic reflection data provided the very high horizontal and vertical resolution necessary for determining continuity of confining units and stratigraphic variations between 10 and 60 m at this site.

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