Nikolas I ChristensenEmeritus Geophysics and Global Tectonics
The focus of my research is the analysis and interpretation of seismic data to better understand crustal and upper mantle composition, genesis and evolution. I have concentrated my efforts on three broad areas of investigation: 1) a study of oceanic crustal structure worldwide, 2) deep crustal structure in continental regions, and 3) P-wave and S-wave analysis of upper mantle seismic anisotropy. An exciting aspect of these investigations is that they are interrelated; progress in any area enhances the understanding of others.
Through federal funding my students and I have developed an outstanding high-pressure facility for measuring physical properties of rocks under in situ crustal and upper mantle conditions. Studies of seismic properties of oceanic and continental rocks have provided much information on the petrology of the Earth's crust and upper mantle. Our experimental capabilities have expanded steadily to keep pace with teaching and research needs. These efforts are helped tremendously by advances in computer hardware and software systems.
Current major projects on which my graduate students and I are working are: 1) analysis and interpretation of seismic refraction data across the South Island of New Zealand; 2) seismic and physical property studies of accreted terranes in British Columbia, Canada; 3) studies of the nature of the layer 2-3 boundary of the oceanic crust; 4) upper mantle anisotropy and crustal structure of the Sierra Nevadas; 5) structure and seismic properties of the San Andreas Fault System in Southern California; 6) a study of the seismic properties of rocks from high pressure metamorphic terranes in China.
I have served on many national, international, and university committees. I have recently been a member of the National Science Foundation Advisory Panel on Instrumentation and Facilities and the Board of Directors of a national committee on continental crustal drilling (DOSECC). I am currently a member of the American Geophysical Union Fellow Selection Committee and the Geological Society of America Committee on Nominations and George P. Woollard Award Selection Committee.
I teach courses ranging from introductory level geology courses to graduate seminars. Graduate level courses which I teach on a regular basis include: Structure and composition of the Earth's Crust, Global Tectonics, and Structural Petrology. In addition, I have been the major advisor to approximately 35 graduate students who have received their M.S. and Ph.D. degrees under my supervision.