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Over the past several weeks, HVO geophysicists have been conducting the annual high-precision Global Positioning System (GPS) survey of Mauna Loa, which supplements HVO's continuous GPS monitoring stations. The annual GPS surveys provide information on vertical and horizontal deformation, informing HVO about the volume changes within subsurface magma reservoirs at Mauna Loa. This station was located on the north flank of Mauna Loa, with Mauna Kea (hugged by clouds on its east side) visible in the background. USGS photo by S. Conway.
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.
