USGS Volcano Notice - DOI-USGS-HVO-2026-07-29T13:10:51+00:00

Activity Summary:  

• Episode 52 of the ongoing Halemaʻumaʻu eruption began around 7:10 p.m. HST July 28 and ended abruptly at 2:36 a.m. HST on July 29, 2026. 
• The maximum lava fountain height was approximately 500 feet (150 meters) above ground level from the north vent. The south vent never fountained during this episode but did emit flames at the end of the eruption. 
• The maximum plume height was approximately 19,000 (5,800 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.  

Episode 52 Chronology: 

Lava fountaining episode 52 in Halemaʻumaʻu at the summit of Kīlauea began around 7:10 p.m. HST July 28 and ended at 2:36 a.m. HST on July 29, 2026, after 7.4 hours of continuous fountaining from the north vent. The last 4 minutes were marked by gas jetting and flames from the north vent. The south vent never fountained during this episode but did emit flames at the end of the episode. The instantaneous effusion rate peaked at about 350 cubic yards (270 cubic meters) per second at approximately 9:15 p.m. HST, with an average effusion rate of 250 cubic yards (190 cubic meters) per second for the entire fountaining episode. An estimated 6.1 million cubic yards (4.7 million cubic meters) of lava erupted and covered about 40-50% of the Halemaʻumaʻu crater floor. Seismicity followed the normal change in tremor patterns seen after most fountain episodes. The Uēkahuna tiltmeter (UWD) recorded about 14.4 microradians of deflationary tilt during episode 52. 

Precursory activity began from the north vent on the morning of July 28 with 6 overflows between 10:22 a.m. HST and 1:53 p.m. HST, the longest lasting over 30 minutes. These were immediately followed by the onset of a vigorous overflow fed by 10-30 foot (3-10 meter) high dome fountains from the north vent at 1:56 p.m. HST which continued until the onset of episode 52 fountaining at 7:10 p.m. HST. The transition was marked by increasing height of the dome fountain, greater eruptive volume, increased deflation and rapidly increasing tremor. 

The north vent lava fountain reached a peak height of approximately 500 feet (150 meters) around 9:00 p.m. HST and produced significant heat and ash, feeding a plume cloud that reached a maximum height of about 19,000 feet (5,600 meters) above sea level based on radar data reported by the National Weather Service (NWS). Winds were out of the northeast during the initial hours of fountaining and caused the plume to move toward the south during the most energetic part of the episode. Later in the evening the lower level winds died and the plume became more vertical but did not spread over populated areas. The plume track largely remained within Hawaiʻi Volcanoes National Park with most tephra falling in the closed area. 

Fountain and plume heights gradually decreased in height to about 400 feet (120 meters) AGL and 10,000 feet (3,000 meters) AMSL, respectively, by 11:00 p.m. HST July 28. Episode 52 ended abruptly at 2:36 p.m. HST on July 29. Fine ash was noted within public areas of Hawaiʻi Volcanoes National Park. No tephra was reported from any other populated areas. 

The abrupt switch from summit deflation to inflation at the end of episode 52 indicates that another lava fountaining episode is likely. 

Published Notices about episode 52:  

Volcano Activity Notice at end of episode 52:  USGS Volcano Notice - DOI-USGS-HVO-2026-07-29T10:09:27+00:00 

Volcano Activity Notice for maximum episode 52 fountain heights: USGS Volcano Notice - DOI-USGS-HVO-2026-07-29T06:14:51+00:00 

Hawaiʻi County Civil Defense Agency message alerting community to potential ash fall: https://evb.gg/n#wshhhoz1s6h/0llV46JE 

HVO short messages posted to the HVO website and social media as episode 52 progressed: HVO - Observatory Messages | U.S. Geological Survey 

Volcano Activity Notice when episode 52 began: USGS Volcano Notice - DOI-USGS-HVO-2026-07-28T22:59:42+00:00 

Hazard Analysis:  

• Volcanic Gas: water vapor (H₂O), carbon dioxide (CO₂), and sulfur dioxide (SO₂) are continuously released during an eruption. SO₂ reacts in the atmosphere to create the visible haze known as vog (volcanic smog) downwind, which may cause respiratory and other problems. 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 the links below: 
• https://seagrant.soest.hawaii.edu/resource-and-guidance-for-volcanic-tephra-fall/   
• https://vog.ivhhn.org/sites/default/files/PelesHair_FAQs_v2.pdf 
• 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 exist around Kīlauea caldera from Halemaʻumaʻu crater wall instability, ground cracking, and rockfalls that can be enhanced by earthquakes. Close to the 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.