USGS Volcano Notice - DOI-USGS-HVO-2025-10-16T21:59:37+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 Static website content will not be updated until further notice and information may become outdated over time.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:

Precursory low-level activity for episode 35 of the ongoing Halemaʻumaʻu eruption increased this morning, October 16, 2025, with a series of lava overflows and drainbacks occurring from the south vent. 

Seven lava overflow-drainback events occurred between 7:47 AM and 1:00 PM HST. A table of event times and durations is provided below. Each overflow produced short, channelized lava flows that flowed onto the crater floor. Each overflow event ended with lava suddenly draining back into the south vent. The drainbacks were immediately preceded by a short burst of spattering or small fountaining in the vent.

Additional overflow-drainback events are expected in the coming hours and days, possibly with increased frequency and/or duration. Similar events occurred during the days leading up to the onset of previous episodes. Approximately 100 overflow-drainback events were observed prior to episode 34 fountaining. Precursory activity prior to previous fountaining episodes has lasted from a few hours to a few days and has included eruptive vent spattering, small dome fountains, lava overflows, and lava drainbacks. Current activity therefore suggests that episode 35 fountaining is likely to begin within the next few days.

Forecast models based on the rate of summit inflation indicate that episode 35 lava fountaining is likely to begin between October 17 and 22, 2025, with the most likely dates being between October 18 and 20. The onset of episode 35 lava fountaining may occur sooner if rates of inflation and precursory activity increase.

Summary of south vent lava overflow/drainback events recorded between 7:47 a.m. and 1:00 p.m. HST, October 16:

Overflow Start time    Overflow End time     Duration (hr:mm)
10/16/25 7:35 AM      10/16/25 7:47 AM      0:12
10/16/25 8:50 AM      10/16/25 9:03 AM      0:13
10/16/25 9:29 AM      10/16/25 9:34 AM      0:05
10/16/25 10:47 AM    10/16/25 10:51 AM    0:04
10/16/25 11:12 AM    10/16/25 11:26 AM    0:14
10/16/25 11:54 AM    10/16/25 12:28 PM    0:34
10/16/25 12:41 AM    10/16/25 12:54 PM    0:13

As reported in this morning's Kīlauea Daily Update, nearly continuous strong glow was visible from both the north and south vents last night, indicating that magma within the conduits is close to the surface. Intermittent spattering in the north vent became visible just after dark last night. Infrequent spattering also occurred from the south vent after 10:00 p.m. HST. Seismic tremor changed from continuous to irregular gas pistoning last night. Kīlauea's summit region continued to inflate over the past 24 hours. The UWD tiltmeter shows continued inflationary tilt and has recovered more than 22 microradians since episode 34 ended. Inflation rates increased on October 15 to approximately 2 microradians per day.

At the start of previous episodes, precursory activity has rapidly escalated into sustained high fountaining over minutes to tens of minutes. During previous episodes, fountains reached heights of more than 1,000 feet (300 meters) and the eruptive plume reached heights of up to 20,000 feet (6,000 meters) above ground level soon after sustained high fountaining began.

Most episodes of Halemaʻumaʻu lava fountaining since December 23, 2024, have continued for around a day or less and have been separated by pauses in eruptive activity lasting generally at least several days. 

• Timeline of eruptive episodes since December 23, 2024: https://www.usgs.gov/volcanoes/kilauea/science/eruption-information.
• All eruptive activity is confined to Halemaʻumaʻu crater within Hawaiʻi Volcanoes National Park.
• Three Kīlauea summit livestream videos that show eruptive lava fountains are available here: V1cam, V2cam, V3cam.
• KPcam and MKcam provide views of the plume height for aviation purposes.

No changes have been detected in the East Rift Zone or Southwest Rift Zone. 

A VAN/VONA will be issued when sustained high lava fountaining begins, marking the start of episode 35.

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 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.