USGS Volcano Notice - DOI-USGS-HVO-2024-09-18T18:09:05+00:00

Activity Summary: Kīlauea volcano continues to erupt in Hawai’i Volcanoes National Park from the new fissure vent that opened within Nāpau Crater yesterday, September 17, morning between 4:00 and 5:00 AM HST. This eruptive episode began with a small eruption that occurred on the evening September 15 from a fissure located just west of Nāpau Crater and lasted a few hours. The eruption is occurring within a closed and remote area of Hawaiʻi Volcanoes National Park. There is no immediate threat to life or infrastructure. Chain of Craters Road, which is closed, is located far downslope and downwind of the eruption. 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: Approximately 8 earthquakes were detected beneath the Kīlauea summit region over the past 24 hours, at depths of 1–3 km (0.6–1.9 mi) below the ground surface, and with magnitudes of 2 or less. The summit tiltmeter at Sandhill continues to record deflation, while the tiltmeter at Uēkahuna has shown little deflation since noon yesterday. This pattern suggests that only the deeper southern summit magma body is now supplying magma 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: This morning, only the vents near the western end of the Nāpau fissure appear to have remained active overnight. At the time of this notice, fountaining could not be observed on the S2cam due to thick fume in Nāpau Crater. The fissure system in Nāpau is about 0.5 km long (.3 mi) and cuts east-west across the northern crater floor. The fissure opened just west of Nāpau early on the morning of September 17 and propagated eastward as the eruption progressed.  Approximately 25-30% of Nāpau Crater floor has been covered by lava, which is confined to the crater. Photos taken during an HVO overflight on September 17 are available here: September 17, 2024 —Kīlauea middle East Rift Zone eruption | U.S. Geological Survey (usgs.gov). Additional eruption information is available in yesterday's Kīlauea daily update: https://volcanoes.usgs.gov/hans-public/notice/DOI-USGS-HVO-2024-09-17T19:43:45+00:00. 

Shallow earthquakes continue to be low in the MERZ with about 60 in the past 24 hours.  Most of these were to the west and northwest of Nāpau Crater. Tiltmeters in the MERZ continue to show no significant changes.  However, daily position solutions from GPS instruments have shown displacements of over 20 cm (8 inches) for several stations in the MERZ.  The largest displacement is for station MKAI, just downslope of Makaopuhi Crater, which has experienced 54 cm (1.8 feet) of south-southwest motion since September 14.  The combination of large GPS displacements and modest tilt rates suggests that much of the deformation is the result of magma entering a storage region several kilometers (1-2 miles) below the surface. 

Sulfur Dioxide (SO₂) emission rates measured yesterday, September 17, were 12,000 tonnes per day in the morning and dropped to 3,700 tonnes per day in the afternoon. This may reflect a decrease in effusion rate or be the result of the two easternmost fissure segments becoming less active late yesterday morning leaving only the westernmost vents active.

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
• September 17 eruption reference map: https://www.usgs.gov/maps/september-17-2024-kilauea-middle-east-rift-zone-eruption-reference-map
• Webpage with eruption-related resources: Eruption on Kīlauea middle East Rift Zone | U.S. Geological Survey (usgs.gov)
• Dynamic monitoring map featuring lava flow polygons is available on the HVO home page: www.usgs.gov/hvo

Analysis: The ongoing MERZ eruption in the region of Nāpau Crater is the first in that area since the multi-day 1997 Napau fissure eruption.  The eruption is currently in its third phase of vent opening and lava production.  Multi-day fissure eruptions are not unusual and at this time it is difficult to say how long the eruptive activity may continue.  Currently, the reduced vent activity, drop in gas emissions, and the reduced deflation of Kīlaueaʻs summit suggest that this eruptive phase is waning.

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. Temporary closures have been implemented as a result of this elevated activity; 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.