Kīlauea’s summit watched closely for possible lava fountaining as early as this weekend

Kīlauea’s summit eruption could produce another episode of lava fountaining as early as this weekend, while a new survey of Mauna Loa shows the neighboring volcano continues to slowly inflate, according to the US Geological Survey’s Hawaiian Volcano Observatory.

The observatory reported that Kīlauea has been erupting episodically within its summit caldera since Dec. 23, 2024, and remains at an advisory alert level. The 51st episode of summit lava fountaining lasted eight hours on July 15. Inflation at the summit since that episode ended suggests another fountaining episode is possible, and current forecast models indicate it could begin between July 25 and 29, the observatory said. It reported no unusual activity along Kīlauea’s East or Southwest rift zones.

Mauna Loa, meanwhile, is not erupting and remains at normal alert level. The observatory said no earthquakes were reported felt across the Hawaiian Islands during the past week.

Mauna Loa GPS survey

Observatory scientists recently completed this year’s survey of Global Positioning System benchmarks on Mauna Loa, part of scientists’ long-running effort to track the volcano’s changing shape.

The observatory relies on a network of permanent GPS stations that provide daily position data, supplemented by annual surveys that gather high-precision measurements at benchmark sites across the island, according to the observatory. Some of those benchmarks have been measured for decades, first using leveling and electronic distance measurement techniques and, since 1994, with GPS instruments.

Twenty-two benchmarks were surveyed this year in a staged deployment spanning several days, the observatory said. Crews set up a GPS antenna, receiver and tripod precisely over each benchmark, then left the equipment in place for three to five days to record data before moving to the next site. That window allows specialized data processing to resolve measurement uncertainties and reduce errors caused by atmospheric effects, according to the observatory.

The results were consistent with trends observed over the past decade-plus, the observatory reported. All benchmarks around the summit moved upward and away from their original locations, while several stations on the volcano’s flanks shifted slightly downward and outward — a pattern the observatory said indicates continued inflation beneath Mokuʻāweoweo, Mauna Loa’s summit caldera. The average rate of ground motion at the summit between 2025 and 2026 was about 2.9 inches (7.4 centimeters) per year, matching rates from earlier campaign surveys and from permanent GPS stations since Mauna Loa’s 2022 eruption.

The largest single change was recorded at site MLCE, on the volcano’s southeast flank, which moved about 5.5 inches (14 centimeters) horizontally to the east-southeast and roughly 3 inches (8 centimeters) vertically upward over the past year, according to HVO.

Despite the continued inflation, HVO said seismicity and gas emissions at Mauna Loa’s summit have remained low and steady, and an eruption is not expected in the immediate future. The observatory said it will continue monitoring ground deformation to give Hawaiʻi residents the earliest possible warning of renewed volcanic unrest.

Mauna Loa is the largest active volcano on Earth and has erupted 34 times since 1843. Its most recent eruption ran from Nov. 27 to Dec. 10, 2022, when fissures opened within Mokuʻāweoweo before vents in the Northeast Rift Zone sent lava flows nearly 12 miles, covering about 16.5 square miles.

The observatory continues to closely monitor both Kīlauea and Mauna Loa. Updates, past Volcano Watch articles, maps and earthquake information are available on HVO’s website. Questions can be emailed to askHVO@usgs.gov.