He has written over 80 papers on the analysis of active volcanoes on Earth using satellite and aircraft data sets, and on the geology of Mars. As an Earth scientist, his work has taken him to some great parts of the world to conduct field experiments, including such places as the Galapagos Islands, the Philippines, Chile, Iceland, Reunion Island, and Antarctica.

His involvement in the SRTM mission focuses on the topographic analysis of volcanoes in Java and the Philippines using the active Kilauea volcano in Hawaii as a calibration target. This work will focus on the shapes of volcanoes in different climatic environments, and the estimation of the volume of features such as lava flows, volcanic craters, and erosional valleys. Such information will be used to better understand the hazards that these volcanoes represent to the local communities.