Judson L. Ahern

Judson L. Ahern
Professor Emeritus, Geophysics
School of Geology & Geophysics
University of Oklahoma
Norman, OK 73019
(405) 325-4480

Personal Pages

Some of the courses I teach:

Geol 1104: The Dynamic Earth
Gphy 3413 Principles of Geophysics
Gphy 4114: Environmental and Geotechnical
Geophysics
Gphy 5713: Solid Earth Geophysics
Gphy 5813: Geomechanics
Gphy 5864: Gravity and Magnetics

Miscellany:

Education:

Ph.D., 1980, Cornell University
M.S., 1975, Ohio State University
B.A., 1973, Ohio Wesleyan University

Nature Stats

Research Interests: Geomechanics; Gravity and Magnetics; Environmental Geophysics.

A few of Dr. Ahern's recent or current research projects include:

Monitoring of artificial aquifer recharge using microgravity. Repeated microgravity surveys have been used to help define underground conduits in a karst aquifer in southwestern Oklahoma.
Analysis of the hundreds of Oklahoma earthquakes recorded in the last ten years to delineate causative structures and investigate possible relationships between oil field activity and microseismicity.
Investigation of the Ames Meteorite Impact Structure in northern Oklahoma, using gravity and magnetics methods.
Suominet Geodetic GPS Project.

Geomechanics involves the application of continuum mechanics and thermal mechanics to problems in the geosciences, such as estimating the rheology and lithosphere in continental interiors based on its deformation due to loading. 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. For example, evidence of billion-year-old rifting of North America, from Minnesota to well into Oklahoma, takes the form of both gravity and magnetic anomalies. 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. On-going research at the Norman, OK landfill involves magnetic surveys looking for ferrous materials and shallow seismic-reflections surveys.

SELECTED PUBLICATIONS

	Ahern, J.L., 1991, Three-dimensional gravity and magnetic model of the southern extension of the Midcontinent Geophysical Anomaly, Northern Oklahoma. EOS, 72, p. 430.
	Hauck, M.L., D. Baird, L. Brown, K.D. Nelson, J. Walters, J. Ahern, A. Jones, Z. Hajnal and L. Sloss, 1992, COCORP deep seismic reflection profiling across the Williston Basin and underlying Trans-Hudson Orogen: acquisition and analysis. EOS, 73, p. 321.
	Ahern, J.L., 1992, Mechanical modeling of the Williston Basin constrained by COCORP seismic reflection profiling. EOS, 73, p. 321.
	Young, R.A. and J.L. Ahern, 1993, Microgravity monitoring of recharge in a karst aquifer in Southwestern Oklahoma. Geological Society of America, Abstracts with Programs, 25, #1, 47.
	Najjar, Y.M., M. Zaman, J. L. Ahern and J. G. Laguros, 1997, Characterization of Ground Subsidence of Abandoned Mines. Proceedings of the Mouchel Centenary Conference on Innovation in Civil and Structural Engineering, 19-21 August, 1997, Cambridge, England.
	Ahern, Judson L., 1997, Gravity and magnetic investigation of the Ames Structure, north-central Oklahoma, in Johnson, K. S.; and Campbell, J. A. (eds.), Ames structure in northwest Oklahoma and similar features: origin and petroleum production (1995 symposium): Oklahoma Geological Curvey Circular 100, p. 330-333.
	Hoyos, Jorge, Roger Young, and Judson Ahern, 1998, Seismic Shear Wave Surveys at the Norman Landfill Site: Geological Society of America 1998 Abstracts with Programs, v. 30, no. 3, p. 8.
	Ahern, Judson L., 1998, Magnetic Surveys at the Norman, OK, Landfill Site: Geological Society of America 1998 Abstracts with Programs, v. 30, no. 3, p. 1.
	Peppler, R. A., F. H. Carr, J. L Ahern, J. C. Liljegren, R. C. Eagan, and J. J. Smith, 2001: SuomiNet efforts in the U.S. Southern Great Plains. Preprints, Fifth Symposium on Integrated Observing Systems, 14-18 January 2001, American Meteorological Society, 218-223.
	Peppler, R. A., F. H. Carr, J. L Ahern, J. C. Liljegren, R. C. Eagan, and J. J. Smith, 2001: SuomiNet efforts in the U.S. Southern Great Plains - Brief Overview. Presented at the Fifth Symposium on Integrated Observing Systems, 18 January 2001, American Meteorological Society Annual Meeting, Albuquerque, NM.