Andria (Andi) P. Ellis

Survey GPS data augment the permanent, continuously recording GPS instruments in HVO's monitoring network. In this photo, a survey tripod is established over a benchmark at Puʻukapukapu, on a remote part of Kīlauea's south flank within Hawai‘i Volcanoes National Park. USGS photo by A. Ellis.

A benchmark on Kīlauea 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. During annual GPS surveys, measurements are made on the benchmarks to allow for comparisons to previous surveys. USGS photo by A. Ellis.

HVO scientists are conducting the annual Kīlauea GPS campaign. During the survey, GPS 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.

This photograph of Kīlauea's ongoing middle East Rift Zone eruption was captured during a Hawaiian Volcano Observatory helicopter overflight during the morning of September 17, 2024. Geologists observed fountaining eruptive fissures and active lava flows bisecting the floor of Nāpau Crater, just downrift (northeast) of the September 15 eruptive fissure.

This photograph of Kīlauea's ongoing middle East Rift Zone eruption was captured during a Hawaiian Volcano Observatory helicopter overflight during the morning of September 17, 2024. Fissures from the previous day's eruption continued to emit steam and gases while new fissures erupted fresh lava in Nāpau Crater. USGS photo by A. Ellis.

USGS Hawaiian Volcano Observatory geologists collected a sample of the middle East Rift Zone Kīlauea eruption in Nāpau Crater, within a closed area Hawaiʻi Volcanoes National Park. Geologists put molten lava into a metal bucket and rapidly quench it with water.

This photograph of Kīlauea's ongoing middle East Rift Zone eruption was captured during a Hawaiian Volcano Observatory helicopter overflight during the morning of September 17, 2024. Geologists observed fountaining eruptive fissures and active lava flows on the floor of Nāpau Crater, just downrift (northeast) of the September 15 eruptive fissure.

HVO staff are conducting the annual Mauna Loa GPS campaign. During the survey, GPS 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.

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.

Another GPS survey benchmark being occupied on Mauna Loa, with views of Hualālai and Haleakalā in the background. USGS photo by A. Ellis.

GPS campaign equipment being staged prior to deployment on Mauna Loa for the annual survey. Temporary GPS receivers and antennas are placed on tripods centered over benchmarks, which serve as a reference point for centering of the antenna. The equipment is left in place to collect data for a couple of days at each site.

A gravimeter being deployed on the floor of Kīlauea caldera, with a GPS station located on a tripod nearby. The gravimeter is the small, shoebox-sized instrument, which can measure a change in the force of gravity to one-in-one billionth of the force you feel every day. USGS photo by A. Ellis.

On March 25, HVO staff and collaborators conducted the annual gravity survey in Kaluapele (the summit caldera of Kīlauea volcano). Measurements of gravity over time can show how mass is distributed beneath a volcano. At Kīlauea, these routine microgravity surveys help the observatory to monitor volcanic activity and to determine changes in gravity. USGS photo by A.

A volcano observatory scientist and a collaborator carry the gravity survey instruments across spatter deposits from the September 2023 Kīlauea summit eruption.

Gravity measurements detect subsurface mass change—for example, magma accumulation or removal beneath the surface. If magma is filling or draining void spaces, it may not be signaled by ground deformation or earthquake activity, but it will be signaled by gravity because of the mass change.

In this photo, taken on October 3, 2023, near Kīlauea's coastline in Hawai‘i Volcanoes National Park, a GPS antenna is mounted on a fixed rod. A GPS receiver, housed in the yellow box, records the positions that can be compared with those from previous years to discern subtle patterns of ground deformation associated with volcanic activity.

Hawaiian Volcano Observatory geophysicists completed the annual GPS survey of Kīlauea. Most Kīlauea and Mauna Loa GPS campaign survey sites have been occupied every year since the early 1990s, whereas the less active volcanoes Hualālai and Haleakalā are surveyed every 3–5 years. USGS photo by A. Ellis.

Hawaiian Volcano Observatory geophysicists recently completed the annual GPS survey of Kīlauea.

During the annual Kīlauea GPS campaign, scientists temporarily deploy a number of GPS instruments at established benchmarks; their recorded positions can be compared with those from previous years to discern subtle patterns of ground deformation associated with volcanic activity.

A GPS site is occupied on the south flank of Kīlauea, inside Hawai‘i Volcanoes National Park, as part of the 2023 annual campaign survey. The survey data will supplement continuous data collected at permanent GPS sites on Kīlauea volcano. The Pacific Ocean is visible in the background. USGS photo by A. Ellis.