USGS Volcano Notice - DOI-USGS-HVO-2025-10-23T17:33:48+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 Static website content will not be updated until further notice and information may become outdated over time.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 lava fountaining. Vents continue to exhibit incandescence, along with a few spots on crater floor lava flows as they cool and solidify. Kīlauea summit inflation continues along with seismic tremor and vent glow indicating that another lava fountaining episode is probable. Preliminary models suggest a likely forecast window of November 2–10 for episode 36.

Summit Observations:

The north and south vents roughly alternated periods of moderate to bright glow overnight. Only a few small spots of incandescence have been seen away from the vents. Most of the secondary lava flow movement after episode 35 appears to have slowed or stopped, but additional movement is still possible in the next few days.

The summit continues to inflate. The Uēkahuna tiltmeter (UWD) has recorded about 1.6 microradians of inflationary tilt over the past 24 hours and an estimated 12 microradians of inflationary tilt since the end of episode 35. Tremor included periodic bursts over the past 24 hours similar to yesterday. 

Plumes of gas continue from both vents this morning and sulfur dioxide (SO₂) gas emissions remain at background levels, typically between 1,200 and 1,500 tonnes per day.

Episode 35 lava fountains began at approximately 8:05 p.m. HST on October 17 and ended at 3:32 a.m. HST on October 18. South vent fountains reached heights of nearly 1,500 feet (460 meters) and north vent fountains reached heights of about 1,100 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. SO₂ emissions from the East Rift Zone remain below the detection limit.

Analysis:

The immediate onset and continuation of inflationary tilt following the end of episode 35 coupled with persistent vent glow indicates another lava fountaining episode is highly likely. Preliminary models indicate episode 36 is likely to occur sometime between November 2 and November 10.    

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.