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Integrated Use Of Continuous Seismic-Reflection Profiling And Ground-Penetrating Radar Methods At John’S Pond, Cape Cod, MassachusettsNormal access

Authors: C.J. Powers, F.P. Haeni and Spence Smith
Event name: 12th EEGS Symposium on the Application of Geophysics to Engineering and Environmental Problems
Session: Hydrology Forum - Geophysical Applications In Hydrologic Mapping
Publication date: 14 March 1999
Organisations: EEGS
Language: English
Info: Extended abstract, PDF ( 1.28Mb )

Continuous seismic-reflection profiling (CSP) and ground-penetrating radar (GPR) surveys
were conducted by the U.S. Geological Survey in April 1998 over the northern part of
John’s Pond, a glacial kettle pond southeast of Otis Air National Guard Base, Cape Cod, Massachusetts.
The surveys were conducted to delineate the types and thickness of sedimentary
units that may control the infiltration of contaminated groundwater into John’s Pond.
Sand-and-gravel deposits, collapse features and recent organic sediments were imaged
with the CSP and GPR methods. Hummocky to chaotic reflections were interpreted as sandand-
gravel deposits. Slightly wavy, parallel reflections located in depressions in the sand-andgravel
deposits were interpreted as filled collapse features. Lower amplitude, horizontal, laminar
reflections were interpreted as organic sediments. Entrapped methane gas within some of
the organic sediments created a reflection zone that obscured deeper reflections in the CSP
The CSP and GPR methods provide complementary information over most of the surveyed
part of the pond. The methods detect similar interfaces, but a particular interface may
produce a stronger reflection in one record than in the other. For example, regions of the pond
containing organic sediments with entrapped methane gas, which prevent penetration of the
acoustic signal, were penetrated and imaged by GPR. Conversely, regions of the pond containing
electrically conductive sediments or deep water, which attenuate the GPR signal, were imaged
using CSP. The CSP and GPR data were interpreted to generate a bathymetric map and a
map of sediment type and thickness beneath John’s Pond.

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