I joined the research staff at LDEO in 1968 and was Appointed Associate Professor in 1973 and Professor in 1977. I study the brittle deformation of the earth, both on the short term: earthquake physics, and the long term: fault mechanics. My work includes experimental rock mechanics, field studies of faulting, and theoretical studies. I have co-authored with students and colleagues over 300 papers on these subjects, and am the author of the leading treatise in this field, now in its third edition: The Mechanics of Earthquakes and Faulting, 3rd ed. Cambridge Univ. Press, 2019. Earlier editions were translated into Japanese and Chinese.
I am a Fellow of the American Geophysical Union and have been awarded the Murchison Medal of the Geological Society (London) and the Harry Fielding Reid Medal of the Seismological Society of America.