(BIVN) – Episode 51 in the ongoing Kīlauea summit eruption ended at 4:46 p.m. HST on Wednesday, July 15th, after 8.3 hours of continuous lava fountaining.
During the episode, maximum lava fountain heights reached approximately 950 feet (290 meters) above ground level from the north vent. The south vent never fountained during this episode, although flames and gas jets were observed.
The maximum height of the plume generated by the episode 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, southwest of the active vents. Some Peleʻs hair was reported falling outside the closed area inside the park, including Uēkahuna overlook and Kaʻu Desert trailhead on Highway 11.
The following episode 51 chronology was provided by the USGS Hawaiian Volcano Observatory:
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.
Huge Lava Fountains Erupt at Kīlauea Summit (July 15, 2026)
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.
