USGS Volcano Notice - DOI-USGS-HVO-2025-05-11T23:01:59+00:00

Activity Summary: 

Episode 21 sustained lava fountaining from the north vent began at 12:45 p.m. HST on May 11, 2025. Dome fountains at the start of new gas-piston cycle evolved into to continuous lava fountains that grew rapidly in vigor and height. North vent lava fountains are 500 feet high (150 m) and are feeding lava flows covering about 10-20% of the floor of Halema'uma'u crater. The south vent is not currently active.

The onset of sustained fountaining was accompanied by a rapid change in summit tilt from inflation to deflation along with a rapid increase in tremor. The Uēkahuna tiltmeter (UWD) recorded approximately 7 microradians of inflationary tilt between the end of episode 20 and the beginning of episode 21 persistent fountaining. 

Episode 21 sustained fountaining was preceded by 4 hours and 45 minutes of precursory low-level activity marked by gas-pistoning events in the north vent cycling from dome fountaining and ponding of lava to vigorous drainbacks.

Each episode of Halemaʻumaʻu lava fountaining since December 23, 2024, has continued for 13 hours to 8 days and episodes have been separated by pauses in eruptive activity lasting less than 24 hours to 12 days.

Strong degassing (50,000 tonnes of SO2 per day estimated) accompanied by tephra and Pele's hair accompany the fountaining.  Winds are from the northeast blowing the plume southwest away from the main viewing areas and communities. 

• Timeline of eruption episodes since December 23, 2024: https://www.usgs.gov/volcanoes/kilauea/science/eruption-information 
• The Kīlauea summit livestream video is available here: https://www.youtube.com/usgs/live

No changes have been detected in the East Rift Zone or Southwest Rift Zone. HVO continues to closely monitor Kīlauea and will issue an eruption update tomorrow morning unless there are significant changes before then. 

Kīlauea Volcano Alert Level/Aviation Color Code remain at WATCH/ORANGE. All current and recent activity is within Hawaiʻi Volcanoes National Park.

Hazards: 

This episodic eruption is occurring within a closed area of Hawai'i Volcanoes National Park. High levels of volcanic gas—primarily water vapor (H₂O), carbon dioxide (CO₂), and sulfur dioxide (SO₂)—are the primary hazard of concern, as this hazard can have far-reaching effects downwind. As SO₂ is continuously released from the summit during an eruption, it will react in the atmosphere to create the visible haze known as vog (volcanic smog) downwind of Kīlauea. SO₂ and vog may cause respiratory and other problems at high concentrations. Further information on vog can be found at https://vog.ivhhn.org/

Additional hazards include Pele's hair and other volcanic fragments from lava fountains. Pele's hair is strands of volcanic glass often produced by lava fountaining activity. Volcanic fragments can fall on the ground within a few hundred yards (meters) of the eruptive vent(s), or downwind of the vent(s). Strong winds may waft light particles, including Pele's hair, to greater distances downwind. Once they are on the ground, Pele's hair can sometimes cluster and tangle together, giving it the appearance of a tumbleweed. The extent of Pele's hair deposition is dependent on lava fountaining activity and current wind conditions. Residents and visitors should minimize exposure to Pele's hair and other volcanic fragments, which can cause skin and eye irritation. More information about how Pele's hair, its hazards, and what to do is available here: https://www.usgs.gov/observatories/hvo/news/volcano-watch-recent-lava-fountains-highlight-peles-hair-hazards. A Frequently Asked Questions document developed for the 2022 Mauna Loa eruption includes information about potential health effects of Pele's hair and is available here: https://vog.ivhhn.org/sites/default/files/FAQ_on_air_quality_and_health_during_Mauna_Loa_eruption_v1.6.pdf

Hawaiian lava flows generally advance slowly downslope, and during this eruption flows have been confined to Halemaʻumaʻu crater and the southwest side of Kaluapele, Kīlauea's summit caldera. 

Other significant hazards also remain around Kīlauea caldera from Halemaʻumaʻu crater wall instability, ground cracking, and rockfalls that can be enhanced by earthquakes within the area closed to the public. This underscores the extremely hazardous nature of Kīlauea's caldera rim surrounding Halemaʻumaʻu crater, an area that has been closed to the public since late 2007.

For discussion of Kīlauea hazards, please see: https://www.usgs.gov/observatories/hawaiian-volcano-observatory/hazards.