USGS Volcano Notice - DOI-USGS-HVO-2026-09-15T17:29:36+00:00

Overview:

Cracks on and near the base of the northwest wall of Halemaʻumaʻu crater erupted lava just north of the vent complex beginning just before 9:00 p.m. HST last night. No fountaining was associated with the new vents which continue to feed a small flow this morning in the northwest corner of the crater floor. Intermittent eruptions of spatter bursts continued to build a small cone around the north vent and sporadic spatter bursts were also observed from the south vent. No precursory lava flows have erupted from the main vent complex since September 12. Summit inflation stalled last night shortly after the new vents opened. The summit region continues to be highly pressurized, but it is not possible to forecast what might happen next. Two possibilities include the new vents erupting continuously or the new vents shutting down and returning all activity to the established vents.

No significant activity has been noted along Kīlauea’s East Rift Zone or Southwest Rift Zone.

A detailed summary of lava fountaining episode 54 on August 25, 2026, can be found below.

NOTE: Significant changes in activity between Daily Updates are posted here: https://www.usgs.gov/observatories/hvo/observatory-messages

Volcano Activity Notice (VAN) for the start of precursory eruptions: https://volcanoes.usgs.gov/hans-public/notice/DOI-USGS-HVO-2026-09-07T20:09:10+00:00

Summit Observations:

Two new vents opened up on and near the base of the northwest wall of Halemaʻumaʻu crater last night, north of the established vent complex. The vents opened in the region of a small earthquake swarm on Sunday night reported in yesterday's update. No earthquakes immediately preceded the vents, which opened passively with no fountaining. The first vent began opening around 8:30 p.m. HST at the base of the crater wall. Initially it was just a small incandescent spot, but it began feeding a lava flow around 9:00 p.m. HST. The second vent opened up about 100 feet (30 meters) up the crater wall just to the south of the initial vent and immediately fed a lava flow. The second flow then stagnated, but the first flow remains active this morning. Summit inflation stalled at about the time the second vent formed last night, and tilt recorded on the UWD tiltmeter remains level this morning. Both vents are at lower elevations than the established vent complex, but on the trend of the original dike that was emplaced in December 2024.

Intermittent spatter bursts continued from the north vent yesterday after slowing yesterday morning. Around 3 p.m. HST, part of the north vent cone collapsed, and spattering picked up in frequency and intensity. The spattering, along with large flames, continued from the north vent all night and into the morning when spattering slowed again. Both the south and west vents glowed most of the night and spatter bursts were periodically observed from the south vent. 

Precursory activity has continued for about 8 days, which is now the longest period of precursory activity since high fountains began after episode 4, and has included 104 overflows. The next longest period of precursory activity was 6.2 days before episode 44. The most overflows recorded was 179 from the north and south vents combined prior to episode 36.

Tremor recorded at Kīlauea's summit has remained relatively uniform and continuous over the past 24 hours. Tremor intensity did not vary appreciably with the new eruptive activity. Over the past 24 hours, 8 small earthquakes were recorded beneath the summit region mostly on the east side of Kaluapele, the summit caldera. There were no earthquakes in the region where the new vents opened last night and the total earthquakes dropped by half from the previous 4 days.

Summit reinflation has been very unsteady since lava fountaining episode 54 on August 25. On September 7 around 3 p.m. HST, inflation at UWD reached a maximum that was higher than when episode 54 began, approximately 13.2 microradians. Following this inflationary high, UWD recorded around 1 microradian of deflation with the onset of precursory lava flows from the north vent. From then on, there was little net change until around 9 p.m. HST on September 10, when slow inflation returned. As of this morning, UWD's inflation remains stalled since about 9 p.m. HST last night. The total inflationary tilt measured on the UWD tiltmeter remains at 15.7 microradians, well above the 12.7 microradians lost during episode 54.

During inter-episode pauses, the sulfur dioxide (SO₂) emission rate from the summit typically varies between 1,000 and 5,000 tonnes per day. Moderate to strong trade winds (10 mph, 5 meters per second or more) are pushing the degassing plume to the southwest of Kīlauea's summit caldera this morning are expected to continue.  Models indicate that gases as well as fine ash and Pele's hair would be transported to the south of Kaluapele if episode 55 fountaining were to begin today.

Recap of Precursory Activity Prior to Today:

Weak spattering from the north vent was first reported at 6:54 p.m. HST on September 6. Sluggish precursory overflows from the north vent started at around 12:45 p.m. HST on September 7 with no dome fountains or spattering. Overflows from the north vent continued intermittently after that, with a total of 104 between September 7 and 12. Overflows lasted from a few minutes to about 2 hours long and were separated by interludes of about 15 minutes to 8 hours. Overflows between September 7-9 became progressively more vigorous and were fed by a dome fountain that reached 15-30 feet (5-10 meters) tall. Two main lava flows formed during these overflows with one making it about a half mile (1 kilometer) to the southwest of the north vent, and the other making it less than half a mile (1 kilometer) to the northeast of the north vent. On September 10, overflows were generally sluggish, less frequent, shorter in duration (less than ten minutes), not fed by a dome fountain, and did not travel as far from the north vent. Overflows on September 11-12 showed more vigor and lasted longer than ten minutes, with dome fountains that grew from 15-30 feet (5-10 meters) to 35-50 feet (10-15 meters) tall and generated lava flows that traveled farther from the north vent than on September 10. Overflows from September 7-12 built a small shield around the north vent which has since been capped by a spatter cone built from strombolian activity that started on September 13 and is ongoing. The spatter cone around the north vent was measured yesterday afternoon, when it was 36-39 feet (11-12 meters) tall.

Rift Zone Observations:

Rates of seismicity and ground deformation remain low in the East Rift Zone and Southwest Rift Zone. SO₂ emissions from the East Rift Zone remain below the detection limit.

Analysis:

The abrupt switch from summit deflation to inflation at the end of lava fountaining episode 54, glow from the vents, overflows, inflation, and continued seismic tremor bursts at Kīlauea summit indicate that another lava fountaining episode could occur. Magma remains shallow in all of the vents, indicating that current conditions remain favorable for the onset of episode 55 fountaining. Additionally, the summit region has significantly exceeded the amount of deflation recorded during episode 54 and is three microradians over the level when that fountaining episode started. The summit region continues to be highly pressurized as indicated by inflation and opening of new vents, but it is not possible to forecast what might happen next. Two possibilities include the new vents erupting continuously or the new vents shutting down returning all activity to the established vents.

Kīlauea has been erupting episodically since December 23, 2024, from two vents (north and south) in Halema‘uma‘u. Lava fountaining episodes, which generally last for less than 12 hours, are separated by pauses of two or more weeks.

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

Summary of episode 54:

A detailed account of episode 54 is given in the HVO Status Report issued on August 25: https://volcanoes.usgs.gov/hans-public/notice/DOI-USGS-HVO-2026-08-26T05:56:38+00:00

• Episode 54 of the ongoing Halemaʻumaʻu eruption began around 10:30 a.m. HST and ended at 7:33 p.m. HST on August 25, 2026, after 9 hours of continuous lava fountaining. 
• The maximum lava fountain height from the north vent was approximately 500 feet (150 meters) above ground level, reached between 12:15 p.m. and 1:00 p.m. HST. Neither the south vent nor the new west vent (formerly the collapse pit) fountained during this episode.
• The maximum plume height was approximately 17,000 feet (5,200 meters) above sea level.
• Most tephra fall was restricted to the closed area of Hawaiʻi Volcanoes National Park, southwest of the active eruptive vents in Halemaʻumaʻu. However, HVO did also receive a report of trace Pele’s hair falling in the Ka‘ū district of the Island of Hawaiʻi.

Resources:

NOTE: HVO’s monitoring network is mostly recovered from recent power- and storm-related outages. Several summit stations will remain offline as we continue working to repair instruments and re-establish connections in our monitoring network.

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
• Short messages tracking the evolution of the lava fountains and eruptive activity can be found here: https://www.usgs.gov/observatories/hvo/observatory-messages
• Three Kīlauea summit livestream cameras 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

Hazards:

This episodic eruption is occurring within a closed area of Hawai'i Volcanoes National Park.

• Volcanic Gas: High levels of volcanic gas—primarily water vapor (H₂O), carbon dioxide (CO₂), and sulfur dioxide (SO₂)—are continually released during an eruption. Emissions can remain locally hazardous in the areas immediately downwind of the vents, even when the vents are not actively erupting. SO₂ reacts in the atmosphere to create vog (volcanic air pollution) downwind. SO₂ and vog may cause respiratory and other problems at high concentrations. Further information on vog can be found at https://vog.ivhhn.org/
• Tephra: Small glassy volcanic fragments—volcanic ash, pumice, scoria, Pele’s hair and reticulite—are created by the lava fountains. A combination of fountaining dynamics and wind conditions determines where tephra fall may occur for any given eruption episode. Larger particles fall near the vents while light particles may be wafted greater distances. These particles may be remobilized during windy conditions following recent eruptive episodes. Residents and visitors should minimize exposure to these fragments, which can cause skin, eye, and respiratory irritation. More information and guidance on tephra fall hazards is available at https://seagrant.soest.hawaii.edu/resource-and-guidance-for-volcanic-tephra-fall/
• Lava flows: Lava on the floor of Halemaʻumaʻu crater and the southwest side of Kaluapele, Kīlauea's summit caldera, remains hot and may slowly move in the days immediately following an eruptive episode.

Other significant hazards exist around Kīlauea caldera from Halemaʻumaʻu crater wall instability, ground cracking, and rockfalls that can be enhanced by earthquakes. Close to the eruptive vents, the tephra material on the crater rim is prone to cracking, slumping, and small landslides that sometimes expose hot and molten material within. 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.