USGS: “A benchmark on Mauna Loa being surveyed by GPS campaign instruments. The metal disk on the ground beneath the tripod is the benchmark, which is cemented to the lava flow surface.” (USGS photo by A. Ellis)

(BIVN) – Mauna Loa has been quiet ever since the late-2022 eruption. The giant Hawaiʻi island volcano is not erupting and the Alert Level remains at NORMAL. 

In order to track the activity in Mauna Loa’s post-eruption phase, scientists are conducting an annual GPS (Global Positioning System) campaign, placing instruments at various locations across the volcano. The USGS Hawaiian Volcano Observatory says the instruments are deployed at established benchmarks “so that their recorded positions can be compared with those from previous years to discern subtle patterns of ground deformation associated with volcanic activity.” 

“Survey GPS data augment the permanent, continuously recording GPS instruments in HVO’s monitoring network,” the USGS explained. 

The equipment is left in place to collect data for a couple of days at each site.

USGS: “In this photo, a survey tripod is established over a benchmark the rim of Moku‘āweoweo, the caldera at the summit of Mauna Loa; Hawai‘i Volcanoes National Park Mauna Loa Summit Cabin is visible in the background of this image.” (USGS image by A. Ellis)

As of the most recent Mauna Loa activity update published on May 2, the USG HVO said data from GPS instruments have recorded “a very slight inflationary trend near the summit as the volcano recovers from the 2022 eruption, and magma replenishes the reservoir system.”

Seismicity beneath Mauna Loa’s summit and upper-elevation flanks has been low over the past month, HVO added, “which is expected for the post-eruption phase of this volcano.”

“Gas and temperature data from a station on Mauna Loa’s Southwest Rift Zone show that H2S averages below 10 ppm, SO2 remains below the detection limit, and fumarole temperatures remain steady at 83°C, all of which are unchanged from previous months,” the scientists wrote.

Mauna Loa is the largest active volcano on planet Earth and covers half of the Island of Hawaiʻi.