Lava fountains diminishing in height since Kīlauea eruption began

The Kīlauea summit eruption that began on Sunday continues this morning. Eruptive activity is confined to the downdropped block and Halemaʻumaʻu crater within Kīlauea’s summit caldera at Hawaiʻi Volcanoes National Park.

Several lava fountains remain active on the western side of the downdropped block within Kīlauea’s summit caldera. Fountain heights have decreased since the eruption onset, but remain at 32-50 feet high this morning, according to Hawaiian Volcano Observatory.

The easternmost vents on the downdropped block and the westernmost vents in Halema‘uma‘u became inactive Monday, and the remaining active vents on the downdropped block span approximately 0.5 miles.

These vents are roughly east-west trending and feed channelized lava flows traveling north and west onto the Halema‘uma‘u crater floor. The eastern rim of Halema‘uma‘u crater has been buried by new lava flows, and pāhoehoe lava flows cover most of the crater floor except high ground formed during previous eruptive activity in the southwest portions of the crater.

Hawaiian Volcano Observatory field crews report fine particles of Pele’s Hair and other tephra being deposited near the Keanakāko‘i Overlook, which is approximately half a mile from the eruption site. As a result, park officials have closed the overlook area to the public.

No unusual activity has been noted along Kīlauea’s East Rift Zone or Southwest Rift Zone. A live-stream video of the eruption is available at https://www.youtube.com/usgs/live.

Effusion rates appear down from initial eruptive rates but remain high. The laser rangefinder is aimed at a western portion of Halema‘uma‘u crater, not near the new eruptive activity, and recorded nearly 16 feet of uplift to this locality since the eruption started.

Summit tilt has remained deflationary over the past 24 hours. Summit seismic activity is dominated by eruptive tremors — a signal associated with fluid movement — with few volcano-tectonic earthquakes.

Volcanic gas emissions in the eruption area are elevated; a sulfur dioxide emission rate of 49,000 tonnes per day was measured Monday afternoon. This is down significantly from the 190,000 tonnes per day measured just after the onset of the eruption on Sunday.

The eruption is causing vog conditions — hazy air pollution caused by volcanic emissions — to return to West Hawaiʻi.

Vog creates the potential for airborne health hazards to residents and visitors, damages agricultural crops and other plants, and affects livestock. For more information on gas hazards at the summit of Kīlauea, see: https://pubs.er.usgs.gov/publication/fs20173017. Vog information can be found at https://vog.ivhhn.org.

Strong winds may waft fine rock particles to areas downwind of erupting vents. People should minimize their exposure to these fine volcanic particles, which can cause skin and eye irritation. 

Other significant hazards also remain around Kīlauea’s summit from Halemaʻumaʻu crater wall instability, ground cracking, and rockfalls that can be enhanced by earthquakes within the area closed to the public. This underscores the extremely hazardous nature of the rim surrounding Halemaʻumaʻu crater, an area that has been closed to the public since early 2008.

• An eruption reference map is available at https://www.usgs.gov/maps/september-11-2023-kilauea-summit-eruption-reference-map.
• Eruption thermal maps are available at https://www.usgs.gov/maps/september-11-2023-kilauea-summit-thermal-map.
• More eruption information is available at: https://www.usgs.gov/volcanoes/kilauea/recent-eruption.
• S2cam was deployed Monday and provides views of the eruption from the caldera floor: https://www.usgs.gov/observatories/hvo/s2cam-kilauea-caldera-downdropped-block-and-halemaumau-crater-looking-west.

For discussion of Kīlauea hazards, please see https://www.usgs.gov/observatories/hawaiian-volcano-observatory/hazards. Click here for the Hawaiʻi Volcanoes National Park’s visitor information.