This digital elevation map of Yellowstone and Grand Teton national parks was overlaid with elevation change data (colors) from Global Positioning System receivers and satellite measurements. A University of Utah study of the data indicates the giant Yellowstone "supervolcano" is rising upward faster than ever observed. The red arrows pointing up represent uplift of the Yellowstone caldera, or volcanic crater, while the downward red arrows show sinking of the land near Norris Geyser Basin. The black arrows indicate lateral or horizontal ground movement. (A higher-resolution version of this image may be obtained from email@example.com)
Adapted by Wu-Lung Chang, University of Utah, from E.V. Wingert in
"Windows into the Earth," Smith and Siegel.