USGS Volcano Notice - DOI-USGS-HVO-2026-07-16T03:55:25+00:00

Activity Summary: 

• 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.

Episode 51 Chronology:

Lava fountaining episode 51 in Halemaʻumaʻu at the summit of Kīlauea began around 8:30 a.m. HST on July 15 and ended abruptly at 4:46 p.m. HST, after 8.3 hours of continuous fountaining from the north vent. The last 2-3 minutes were marked by gas jetting from the north vent. The south vent never fountained during this episode but did emit flames and gas jets. The instantaneous effusion rate peaked at about 370 cubic yards (280 cubic meters) per second at approximately 10:30 a.m. HST, with an average effusion rate of 200 cubic yards (150 cubic meters) per second for the entire fountaining episode. An estimated 6.6 million cubic yards (5.1 million cubic meters) of lava erupted and covered about 50% of the Halemaʻumaʻu crater floor. Seismicity followed the normal change in tremor patterns seen after most fountain episodes. There was one locatable earthquake associated with the eruption: a shallow magnitude-2 event at 14:52:59 HST located beneath the southeast corner of Halema'uma'u crater. The Uēkahuna tiltmeter (UWD) recorded about 14.7 microradians of deflationary tilt during episode 51.

Precursory activity began from the north vent on the afternoon of July 14 with 4 overflows between 3 and 4 p.m. HST, the longest lasting over 30 minutes. Activity then paused when inflation leveled off. Summit inflation resumed later in the evening. Overflows began from the south vent at 2:08 and 2:32 a.m. HST on July 15, and each lasted less than 5 minutes. After a brief pause, short overflows from the north vent occurred at 4:27 and 4:42 a.m. HST. 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 4:47 a.m. HST which continued until the onset of episode 51 fountaining around 8:30 a.m. HST. The transition was marked by increasing height of the dome fountain, greater eruptive volume, increased deflation and tremor.

The north vent lava fountain reached a peak height of approximately 950 feet (290 meters) around 10:30 a.m. HST and produced significant heat and ash, feeding a plume cloud that reached a maximum height of about 18,000 feet (5,500 meters) above sea level based on radar data reported by the National Weather Service (NWS) and verified by HVO webcam images. Winds were out of the northeast during the initial hours of fountaining and caused the plume to move toward the southwest during the most energetic part of the episode. High level winds from the south blew the upper plume toward the northwest after 10:00 a.m. HST. The NWS issued an updated Special Weather Statement (SWS) at 10:26 a.m. HST indicating that varying levels of ash, Pele`s hair, and other lightweight tephra may fall downwind of the eruption. 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 4:40 p.m. HST. Then the episode ended abruptly at 4:46 p.m. HST. No tephra was reported from any populated areas.

The abrupt switch from summit deflation to inflation at the end of episode 51 indicate that another lava fountaining episode is likely.

Published Notices about episode 51: 

Volcano Activity Notice at end of episode 51: USGS Volcano Notice - DOI-USGS-HVO-2026-07-16T01:02:30+00:00

Volcano Activity Notice for maximum episode 51 fountain heights and reports of tephra fall in Hawai'i Volcanoes National Park: https://volcanoes.usgs.gov/hans-public/notice/DOI-USGS-HVO-2026-07-15T20:15:42+00:00

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

HVO short messages posted to the HVO website and social media as episode 51 progressed: HVO - Observatory Messages | U.S. Geological Survey

Volcano Activity Notice when episode 51 began: https://volcanoes.usgs.gov/hans-public/notice/DOI-USGS-HVO-2026-07-15T01:41:41+00:00

Kilauea Daily Update for July 15 prior to the start of episode 51: https://volcanoes.usgs.gov/hans-public/notice/DOI-USGS-HVO-2026-07-15T15:48:14+00:00

Volcano Activity Notice issued on July 14 when precursory low-level eruptive activity before episode 51 began: https://volcanoes.usgs.gov/hans-public/notice/DOI-USGS-HVO-2026-07-15T01:00:23+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.