Many continental interiors are remote from plate boundaries and thus have been relatively stable throughout more recent geologic time. Continental lithosphere beneath intracratonic basins, however, appears to undergo slow cooling, thickening, and subsidence, following a heating event that is not yet understood. This research involves computer modeling, as constrained by stratigraphic data, potential field data, seismic data, and geochemical and radiometric data. Earth's gravity and magnetic fields provide subtle clues to the structure of its interior. Currently, Dr. Ahern is investigating the gravity and magnetic signature of the Ordovician Ames Meteorite Impact Structure in northern Oklahoma that has proved to be an important oil-producing structure.
Environmental geophysics differs from crustal or global geophysics mostly in scale.
Gravity and magnetic surveying methods, for example are as applicable to shallow targets as deep ones. Surveys are designed to emphasize high resolution of the near-surface rather than depth of penetration. A recent project involved repeated microgravity over a karst aquifer to use gravity variation with water-table level to infer porosity of the aquifer. Oklahoma Geological Curvey Circular 100, p. 330-333. 1998 Abstracts with Programs, v. 30, no. 3, p. 8.