Kīlauea Gravity Survey - April 2022

During a gravity survey, HVO scientists measure the relative strength of gravity (using a gravimeter, one of the small light-colored boxes in the center of the photo) between benchmarks. At each benchmark, the effects of elevation changes are corrected using high-precision vertical positions from kinematic Global Positioning System (using a GPS, on a tripod and antenna in the foreground of the photo). USGS photo by A. Ellis.