USGS Volcano Notice - DOI-USGS-HVO-2025-10-20T18:46:01+00:00

During the lapse in appropriations, the USGS Hawaiian Volcano Observatory (HVO) continues to maintain monitoring networks and issue updates and notifications of volcanic activity via the Hazard Notification Service. Volcano monitoring data will continue to be available on the HVO website. Static website content will not be updated until further notice and information may become outdated over time. For more information on the shutdown, please visit the Department of the Interior website at www.doi.gov.

Activity Summary:

Episode 35 of the ongoing Halemaʻumaʻu eruption ended on October 18 after 7.5 hours of continuous fountaining. Vent areas and lava flows continue to exhibit slow movement and/or incandescence as they cool and solidify. Kīlauea summit inflation immediately resumed following the end of episode 35 and continues along with tremor and vent glow. These observations indicate that another fountaining episode is probable, but likely at least two weeks away. 

Summit Observations:

Intermittent glow, and possibly some flames, continued from both the north and south vents throughout the night, though the north vent was more persistent. Remobilized flows were sluggishly active through yesterday on the slopes around the cone. Additional secondary flows and creep of agglutinated tephra is possible in the coming days.

The summit continues to inflate. The Uēkahuna tiltmeter (UWD) recorded 2.5 microradians of inflationary tilt over the past 24 hours and 7.2 microradians of inflationary tilt since the end of episode 35. Tremor shows small spikes about every 5 minutes that are characteristic of gas pistoning of magma within the vents.

Plumes of gas are rising from both vents this morning and sulfur dioxide gas emissions remain at background levels, typically between 1,200 and 1,500 tonnes per day.

Episode 35 fountains began at approximately 8:05 p.m. HST on October 17 and ended at 3:32 a.m. on October 18. South vent fountains reached heights of nearly 1,500 feet (460 meters) and north vent fountains reached heights of about 1100 feet (330 meters). These were the highest single fountain and highest pair of fountains seen during this eruption so far. Episode 35 fountains produced an estimated 13 million cubic yards (10 million cubic meters) of lava. The combined average eruption rate was over 500 cubic yards per second (400 cubic meters per second) from the dual fountains. Lava flows from the fountains covered about two thirds of the floor of Halemaʻumaʻu crater.

The following notices provide more information about episode 35:

• USGS Volcano Notice - DOI-USGS-HVO-2025-10-18T20:28:54+00:00
• USGS Volcano Notice - DOI-USGS-HVO-2025-10-18T10:16:28+00:00
• USGS Volcano Notice - DOI-USGS-HVO-2025-10-18T07:33:48+00:00
• USGS Volcano Notice - DOI-USGS-HVO-2025-10-17T05:15:25+00:00
• USGS Volcano Notice - DOI-USGS-HVO-2025-10-16T21:59:37+00:00

The following links provide more information about the current eruption that began on December 23, 2024:

• Eruption resources, including the most recent map and a timeline of eruption episodes since December 23, 2024: https://www.usgs.gov/volcanoes/kilauea/science/eruption-information
• Three Kīlauea summit livestream videos that show eruptive lava fountains are available here: https://www.youtube.com/@usgs/streams
• Summit eruption webcams: https://www.usgs.gov/volcanoes/kilauea/summit-webcams
• Volcano Watch article on gas pistons: https://www.usgs.gov/observatories/hvo/news/volcano-watch-so-what-earth-or-least-kilauea-a-gas-piston

Rift Zone Observations:

Rates of seismicity and ground deformation remain very low in the East Rift Zone and Southwest Rift Zone, with no significant earthquake activity in the past 24 hours outside of the summit. Sulfur dioxide (SO₂) emissions from the East Rift Zone remain below the detection limit.

Analysis:

The onset of inflationary tilt following the end of episode 35 indicates that the summit magma reservoir is repressurizing, as in previous episodes, and may produce another lava fountaining episode in the future. More time and data are needed to model forecast windows and determine when a subsequent lava fountaining episode is likely to occur. However, the next episode is likely at least two weeks away based upon the overall deflation of the summit during episode 35.  

The current eruption has been characterized by episodic lava fountaining not seen in any eruptions since the 1983–86 episodic fountains at the beginning of the Puʻuʻōʻō eruption. Lava fountains and flows have erupted from two vents within Halemaʻumaʻu crater that we refer to as the north vent and south vent. Each of the previous fountaining episodes lasted from a few hours to over a week and was accompanied by strong deflation of the summit region. Pauses between the lava fountaining episodes have been marked by an immediate switch from deflation to inflation as the magma chamber recharges and repressurizes. Lava fountaining episodes have occurred approximately once per week since the start of the current eruption on December 23, 2024.

HVO continues to closely monitor Kīlauea and is in contact with Hawai‘i Volcanoes National Park and the Hawai‘i County Civil Defense Agency about eruptive hazards.

Please see the Hawaiʻi Volcanoes National Park website for visitor information: https://www.nps.gov/havo/index.htm

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 one major 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/

Another major hazard is fallout of Pele's hair and other volcanic fragments from lava fountains. Pele's hair is strands of volcanic glass often produced by lava fountaining activity that can be carried well over 10 miles (15 kilometers) from the vent. Other hot glassy volcanic fragments (tephra) including volcanic ash, pumice, scoria, and reticulite can fall on the ground within 1–3 miles (1–5 kilometers) of the eruptive vent(s), with the highest concentrations immediately downwind of the vent(s). Various volcanic fragments have fallen on Highway 11 west of Hawai'i Volcanoes National Park at times, depending on wind and eruption conditions. Strong winds may waft light particles, including Pele's hair, to greater distances downwind. Once 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 wind conditions. Residents and visitors should minimize exposure to Pele's hair and other glassy volcanic fragments, which can cause skin and eye irritation and can also contaminate catchment water supplies. 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 recently updated Frequently Asked Questions document that includes information about potential health effects of Pele's hair is available here: https://vog.ivhhn.org/sites/default/files/PelesHair_FAQs_v2.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.