USGS Volcano Notice - DOI-USGS-HVO-2026-07-23T18:31:05+00:00

Overview:

The summit eruption of Kīlauea in Halemaʻumaʻu is paused. Strong glow and flaming at south vent, steady glow at north vent, and the resumption of summit inflation over the past 24 hours has adjusted the modeled forecast time window for episode 52 fountains to between July 25 and July 29.  

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

A summary of episode 51 is posted below.

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

Summit Observations:

Degassing continues from both north and south vents. Strong glow and occasional flaming was visible overnight from the south vent, while north vent had weaker yet fairly persistent glow.

Tremor remains continuous and still has occasional small, ragged tremor bursts. No earthquakes were located beneath the summit of Kīlauea summit in the past 24 hours. 

Since episode 51 ended, inflation resumed and has recovered 11.1 microradians of tilt at the summit tiltmeter at Uēkahuna (UWD). Summit inflation resumed in the past 24 hours after a day-long pause. Kīlauea summit deflation totaled 14.7 microradians during episode 51.

The sulfur dioxide (SO₂) emission rate from the summit is likely now varying within a typical range of 1,000 to 5,000 tonnes per day. Degassing plumes from both vents are being blown toward the southwest this morning.

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 episode 51 along with continued glow from the vents indicates that another fountaining episode is likely. Inflation since the end of episode 51 was relatively smooth without significant deflations until very early on Tuesday, July 21, when inflation paused and was flat for over a day. Inflation resumed yesterday morning (Wednesday July 22), and has since gained 2 microradians. As of this morning, inflation-based models have moved the forecast window for the start of episode 52 fountains a day earlier to July 25 through July 29. Future periods of slow inflation or deflation may cause the forecast window to be adjusted.

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 that can be longer than three 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 51:

A detailed account of episode 51 is given in the HVO Status Report issued on July 15: https://volcanoes.usgs.gov/hans-public/notice/DOI-USGS-HVO-2026-07-16T03:55:25+00:00

• Episode 51 of the ongoing Halemaʻumaʻu eruption began around 8:30 a.m. HST on July 15 and ended abruptly at 4:46 p.m. HST on July 15, 2026.
• The maximum lava fountain height was approximately 950 feet (290 meters) above ground level from the north vent. The south vent never fountained during this episode but did emit flames and gas jets.
• The maximum plume height was approximately 18,000 (5,500 meters) above mean sea level.
• Tephra fall was restricted mostly to the closed area of Hawaiʻi Volcanoes National Park to the southwest of the active Halemaʻumaʻu vents. A light fall of Peleʻs hair was reported at several sites in the national park outside the closed area, including Uēkahuna overlook and Kaʻu Desert trailhead on Highway 11.

Resources:

NOTE: HVO’s monitoring network is mostly recovered from recent power- and storm-related outages. Several summit stations, including the SDH tiltmeter, will remain offline until we are able to re-establish access across the deep tephra field southwest of the caldera.

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.