Global Positioning System (GPS) is used to track deformation (ground surface changes) on Hawaiian volcanoes. Here, an HVO geophysicist completes the final setup on a GPS instrument on KÄ«lauea so that it can begin collecting data on the volcano’s lower East Rift Zone. USGS photo by L. DeSmither. Photo taken Tuesday, February 19, 2019 courtesy of U.S. Geological Survey