A MULTI-METHOD NEAR-SURFACE GEOPHYSICAL STUDY ON THE NOSE HILL UPLAND

Darryl G. Parry

ABSTRACT

Five different geophysical techniques: ground penetrating radar (GPR), fixed frequency electromagnetics (EM), vertical electrical soundings (VES), seismic refraction and reverse vertical seismic profiling (RVSP) were applied during an investigation of the near-surface of the earth on the Nose Hill upland in northwest Calgary. These techniques tested radio, very low, and DC frequency electrical properties and elastic wave seismic properties of the shallow geological material at three survey sites.

The seismic velocity structure obtained via RVSP and refraction surveys revealed local stratigraphy and implied lithology. The addition of shear wave information identified probable climactic induced variations in water saturation. Refraction surveying was more successful in this locale than was RVSP, as logistical difficulties hampered the absolute location of seismic sources for the latter experiment.

The stratigraphic image produced seismically was supported by VES. The results produced by this electrical method suggested that GPR would be unsuccessful in areas with thick till cover. EM surveying allows an assessment of local electrical homogeneity and an areal extension of the VES interpretation. Where tills have been removed, GPR surveying was very effective and produced a clear, detailed picture of the braid plain gravels.

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