Sieh's principal research interest is earthquake geology, which uses geological layers and landforms to understand the geometries of active faults, the earthquakes they generate, and the crustal structure their movements produce. His early work on the San Andreas fault led to the discovery of how often and how regularly it produces large earthquakes in southern California.
Sieh received his undergraduate degree in geology from the University of California, Riverside in 1972 and his Ph.D. degree in geology from Stanford University in 1977. He was a professor of geology at the California Institute of Technology from 1986 to 1999. Sieh is a member of the United States National Academy of Sciences (since 1999).
Awards and honors 
Awards and Honors:
- GLBT Scientist Award, National Organization of Gay and Lesbian Scientists and Technical Professionals, 2006
- Fellow, American Geophysical Union, 2001
- National Academy of Sciences, member, 1999
- Fellow, Geological Society of America, 1996
- National Academy of Sciences Award for Initiatives in Research, 1982
- E.B. Burwell, Jr., Memorial Award of the Engineering Geology Division, Geological Society of America, 1980
- "Geology of Earthquakes" with Robert S. Yeats and Clarence R. Allen. Oxford University Press (1997) ISBN 0-19-507827-6
- "The Earth in Turmoil: Earthquakes and Volcanos and Their Impact on Humankind" with Simon LeVay. W. H. Freeman & Sons (1998) ISBN 0-7167-3151-7
- "Living on an Active Earth: Perspectives on Earthquake Science" as part of the Committee on the Science of Earthquakes, National Research Council. National Academies Press (2003) ISBN 0-309-06562-3