Current Research

My research aims to understand how the upper part of Earth’s crust responds to active contraction along plate boundaries and within continental interiors. I am interested in how movements caused by earthquakes on buried faults are transferred upward into overlying, mountain-sized wrinkles, or folds. My research is driven by the societal need to forecast the locations of future earthquakes in densely populated areas, and the scientific aim of understanding the physical mechanisms that govern growth of folds.

My graduate students and I study actively growing folds in Southern California, the New Madrid seismic zone in the American midcontinent, Japan and Taiwan. I use folds formed at Earth’s surface as a proxy for characterizing the behaviour of earthquakes on blind thrusts because these faults pose a threat to a number of major cities and cannot be assessed by traditional methods.

Besides study of active folds, my group has sought to understand why recent uplift of southern California and northern Baja California occurs and whether it is related to active folding above buried faults. Our work attributes uplift of the Baja Peninsula to mantle-derived bouyancy produced by rifting in the nearby Gulf of California, and not movement on buried faults.

I am also interested in understanding how feedback mechanisms operate to govern the interplay between erosion and mountain building and have undertaken new work using Taiwan as a type area. We seek to test whether a portion of the orogen is currently stepping hindward in response to accelerated erosion.

Another new aspect of my research program is aimed at understanding the tectonic history of a portion of Mars using a topographic model gathered by a NASA spacecraft. We seek to define the kinematic development of "wrinkle ridges" or fault-propagation folds developed around the margin of the giant volcanic edifice of Tharsis, in particular on the ridged plains of Lunae and Solis Plana.

See the following links to more detailed descriptions and image galleries of work in my group.

Southern California - Slip rates and geometry of fault-related folds in the Los Angeles basin for analysis of blind thrust earthquake hazards. Origin of regional uplift in the Peninsular Ranges Province and its relation to mantle bouyancy and subsidence. Work in southern California is in collaboration with researchers at the Southern California Earthquake Center (SCEC), San Diego State University and Harvard University.

The Planet Mars - Kinematics, scaling relationships and crustal structure from fault-related folds on the giant volcanic province Tharsis. Digital elevation models from the Mars Orbiter Laser Altimeter (MOLA) are used with structural analogues of terrestrial folds to define Hesperian shortening and its implications for the thermal structure and regional strain on Mars early in its history. This project is in collaboration with researchers at JPL.

Taiwan - Late Quaternary deformational and erosional history of the west-central Taiwanese orogen in collaboration with colleagues at National Taiwan University. Includes field mapping, analysis of digital elevation models and structural restorations in a classic thin-skinned thrust belt.

Japan - Structural analysis and assessment of seismic hazards posed by blind thrusts in metropolitan Osaka, Tokyo, Kyoto and Nagoya. This work is in collaboration with colleagues at the Active Fault Studies Group of the Japanese Geological Survey, the Geo-Research Institute of Osaka, Kyoto University and Bukkyo University.

New Madrid - Structural analysis, paleoseismology and geomorphology of active folding across the Reelfoot thrust in collaboration with colleagues at the University of Arkansas and the Center for Earthquake Research and Information (CERI), at the University of Memphis.