Penn Arts & Sciences Logo


Christopher A. Thom

PhD Candidate


  • A.B. (2011-2014) with Research Distinction, Geochemistry, Washington University in St. Louis 
  • Ph.D Candidate (2014-present), Earth and Environmental Science (Geophysics focus), University of Pennsylvania

Research Interests

My research interests lie at the intersection of geophysics, materials science, and engineering.  I utilize non-traditional rock deformation techniques such as nanoindentation to measure the rheology of a wide range of geologic materials, including olivine, quartz, calcite, halite, and ice.  I also use the D-DIA apparatus to measure the strength of geologic materials at room and elevated temperature to determine the physical mechanisms that limit deformation.  I am also interested in the mechanics of earthquake nucleation and the general behavior of faults.  I have used atomic force microscopy, white light interferometry, and nanoindentation to examine the scale dependences of roughness and strength in exhumed faults to determine how stresses are distributed in a fault system.  I am also interested in using contact mechanics simulations and single asperity friction experiments to elucidate the physical mechanisms that give rise to friction and ultimately, earthquakes.

Selected Publications

Thom, C.A., Brodsky, E.E., Carpick, R.W., Pharr, G.M., Oliver, W.C., and Goldsby, D.L., Nanoscale roughness of natural fault surfaces controlled by scale-dependent yield strength. Geophysical Research Letters, 44, (2017). DOI: 10.1002/2017GL074663 

Kumamoto, K. M., Thom, C.A., Wallis, D., Hansen, L.N., Armstrong, D.E.J., Warren, J.M., Goldsby, D.L., and Wilkinson, A.J., Size effects resolve discrepancies in 40 years of work on olivine plasticity. Science Advances, 3, e1701338 (2017). DOI: 10.1126/sciadv.1701338

Thom, C.A., Carpick, R.W., and Goldsby, D.L., Constraints on the physical mechanism of frictional aging of rocks from nanoindentation. (in review).

Hansen, L.N., Thom, C.A.,Kumamoto, K.M., Wallis, D., Durham, W.B., Goldsby, D.L., and Kohlstedt, D.L., Low-temperature plasticity in olivine: Grain size, strain hardening, and the strength of the lithosphere. (in review).

Thom, C.A. and Goldsby, D.L. Studies of plasticity and dislocation creep in single crystal halite by nanoindentation. (in prep.)


  • American Geophysical Union (AGU)
  • Geological Society of America (GSA)
  • Southern California Earthquake Center (SCEC)
  • Advanced Photon Source (APS)

Department of Earth and Environmental Science / University of Pennsylvania, 251 Hayden Hall, 240 South 33rd Street, Philadelphia, PA 19104-6316