Volcano Updates

Activity Summary: The current eruption of Kīlauea volcano remains paused since the morning of September 20.  Minor glow from the vent and small spots on the flows were visible yesterday evening, but mostly disappeared by early morning.  Degassing from the vent continues with the gas plume moving to the southwest this morning.   The eruption site is within a closed and remote area of Hawaiʻi Volcanoes National Park. There is no immediate threat to life or infrastructure. Residents of nearby subdivisions may experience volcanic gas emissions related to this activity which may increase and decrease over the coming hours and days. The Volcano Alert Level/Aviation Color Code remains at WATCH/ORANGE. No changes have been detected in the lower East Rift Zone or Southwest Rift Zone. 

Summit Observations:  Eight small, shallow earthquakes were detected beneath the Kīlauea summit region over the past 24 hours. The tiltmeter at Uēkahuna remains flat, showing no deflation. The summit tiltmeter at Sandhill continues to record deflation, but at a significantly decreased rate compared to the onset of the eruption on September 16. This pattern suggests that only the deeper, southern summit magma body is continuing to supply magma at a decreased rate to the middle East Rift Zone. The most recent measurement of SO₂ emission rate at the summit was 60 tonnes per day on September 17, 2024.   

Rift Zone Observations:  The eruption near Nāpau Crater remains paused since the morning of September 20.  Glow from the vent and flows died out overnight and very little glow was visible this morning. Degassing continues at a very low rate producing about 80 tonnes per day of SO₂ as measured yesterday afternoon, September 21.  The gas plume is currently moving southwest from the vent due to normal trade winds.

Lava flows from this eruption have covered about 2/3 (500,000 square meters or 125 acres) of the floor of Nāpau Crater.  In total, this eruption has covered more than 630,000 square meters (156 acres) of Nāpau Crater and areas to the west since Sunday night.  Approximate effusion rates of roughly 5-15 cubic meters per second (6-16 cubic yards) were estimated during the most active part of the fissure eruption on September 19. 

Shallow earthquake counts remain very low in the MERZ with about 8 in the past 24 hours. Little or no tremor is being recorded on the MERZ seismometers close to the eruption site.  Tiltmeters in the MERZ continue to show no significant shallow deformation and GPS instruments show greatly decreased inflation at deeper levels beneath the area between Maunaulu and Nāpau Crater. 

All activity is currently confined to the middle East Rift Zone between Makaopuhi Crater and Puʻuʻōʻō and there are no indications of any changes further downrift in the MERZ or in the LERZ. 

Additional Resources 

• New S2cam, viewing the eruption from the east: https://www.usgs.gov/observatories/hvo/s2cam-view-napau-crater-east-rift-zone-kilauea-view-southwest 
• Webpage with eruption-related resources: Eruption on Kīlauea middle East Rift Zone | U.S. Geological Survey (usgs.gov) 
• Rapidly updated eruption monitoring map showing lava flow coverage and vent locations is available on the HVO home page: www.usgs.gov/hvo  
• Mapping data and a fully zoomable version of eruption monitoring map are available here: USGS Hawaii eruption map - preliminary (arcgis.com) 

Analysis: The fourth phase of activity in ongoing MERZ eruption is over and the eruption remains paused. Tremor remains very low indicating eruptive activity is not occurring at this time.  Each eruption has increased in volume compared to the prior eruption so far in this sequence, possibly due to flushing of cooler magma stored during previous eruptions in this region.   Multi-day fissure eruptions are not unusual in this area with over a dozen in the past 200 years.  These are typically short, lasting 1-10 days covering relatively small areas similar to this eruption.  The current eruptive activity appears to be linked to the continuing supply of magma from the summit. The magma supply rate from the summit has diminished over the past several days compared to rates at the eruption onset. Inflation detected by GPS instruments in the MERZ has also slowed. At this time, it is unlikely that this eruption will restart. 

Updates: HVO is continuing to closely monitor the middle East Rift Zone and is in contact with Hawai‘i Volcanoes National Park and the Hawai‘i County Civil Defense Agency. Please see the Hawaiʻi Volcanoes National Park website for visitor information: https://www.nps.gov/havo/index.htm. HVO will continue to provide daily updates for Kīlauea volcano. Should volcanic activity change significantly, a Volcanic Activity Notice will be issued.  

Hazards: High level of volcanic gas—primarily water vapor (H₂O), and sulfur dioxide (SO₂)—are emitted during eruptions and can have far-reaching effects downwind. As SO₂ is released from lava, it reacts in the atmosphere to create the visible haze known as vog (volcanic smog) that has been observed downwind of eruptive vents. 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, please see: https://pubs.er.usgs.gov/publication/fs20173017. Vog information can be found at https://vog.ivhhn.org.    

Shallow magma movement and eruptions can produce minor to severe ground fractures and subsidence features, which can affect the landscape, human activity, and infrastructure. These ground cracks can continue to widen and offset as magma migration continues, may have unstable overhanging edges, and should be avoided.  

Additional ground cracking and outbreaks of lava around the active fissures are possible at any time, or existing fissures can be reactivated. Hawaiian lava flows generally advance slowly downslope and can be avoided by people. They can destroy everything in their paths including vegetation and infrastructure—which can cut off road access and utilities. Hazards associated with active or recent lava flows include hot and glassy (sharp) surfaces that can cause serious burns, abrasions, and lacerations upon contact with unprotected or exposed skin; uneven and rough terrain can lead to falls and other injuries; hot temperatures that can cause heat exhaustion or dehydration, or in heavy rain can produce steamy ground-fog that can be acidic, severely limiting visibility and sometimes causing difficulty breathing.   

If new lava flows cover and burn vegetation and soil, they can ignite natural gas pockets in the subsurface, which can cause methane explosions. These explosions can blast lava fragments up to several meters (yards) away and can be hazardous to observers. 

Pele's hair and other lightweight volcanic glass fragments from lava fountains and spattering will fall downwind, dusting the ground within a few hundred meters (yards) of the vent. High winds may waft lighter particles and transport them greater distances downwind. Exposure to these volcanic particles can cause skin and eye irritation. 

Hazards remain around Kīlauea caldera 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.  

For discussion of Kīlauea hazards, please see: https://www.usgs.gov/observatories/hawaiian-volcano-observatory/hazards.