Another GPS survey station that was recently occupied during the annual Mauna Lo

Another GPS survey station that was recently occupied during the annual Mauna Loa GPS survey campaign. The disk-shaped GPS unit is placed on top of a tripod, which allows the GPS to be positioned exactly above the benchmark (the round metal plate on the surface of the lava flow). HVO has been conducting annual GPS surveys since the mid-1990s, allowing HVO to calculate how individual points (benchmarks) on Mauna Loa have moved compared to prior years. You can read more about GPS use in volcano-monitoring in this "Volcano Watch" article. USGS photo by S. Conway.