USGS Volcano Notice - DOI-USGS-HVO-2024-09-23T18:36:45+00:00

Activity Summary: The eruption of Kīlauea volcano in and near Nāpau Crater has ended.  Only a couple of intermittent small spots of residual glow could be detected on the flow field last night.  Weak degassing from the vent continues with the gas plume moving to the southwest this morning. Geophysical signatures of eruptive activity have all returned to background levels. The Volcano Alert Level/Aviation Color Code was lowered from WATCH/ORANGE to ADVISORY/YELLOW earlier this morning. No changes have been detected in the lower East Rift Zone or Southwest Rift Zone.  

Summit Observations:  Six 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 very weak deflation, but at a rate that is less than 10% of that recorded during eruptive activity. This pattern suggests that very little if any magma is moving from the summit 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 middle East Rift Zone (MERZ) eruption near Nāpau Crater has ended. The last eruptive activity stopped around 10 AM HST on the morning of September 20.  Only minor intermittent glow can be seen from the eruption site at night since that time.  Degassing continues at a very low rate producing about 80 tonnes per day of SO₂ as measured September 21. The gas plume is currently moving southwest from the vent due to normal trade winds.  

Shallow earthquake counts remain very low in the MERZ with about 13 in the past 24 hours. Tremor is no longer being recorded on seismometers close to the eruption site.  Tiltmeters in the MERZ continue to show no significant shallow deformation and GPS instruments show a major decrease or cessation of inflation at deeper levels beneath the area between Maunaulu and Nāpau Crater.  

All recent activity was 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.  

 Analysis:  The eruption in and near Nāpau Crater had four eruptive phases between September 15 and September 20. The final eruptive activity from a small vent west of Nāpau Crater ended at about 10 AM HST on September 20. All observable and instrumental signs of potential for renewed eruptive activity have declined since that time. Seismicity in the area is extremely low and tremor, characteristic of magma within vents, is no longer being recorded by seismometers in the area. In addition, the ground deformation data that showed magma was moving from the summit to the middle East Rift Zone has slowed dramatically or stopped altogether. Volcanic gas emissions have decreased to near background levels. All of these factors indicate that this eruption has ended. 

 Lava flows from this eruption 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. A webpage with eruption-related resources is available here: Eruption on Kīlauea middle East Rift Zone | U.S. Geological Survey (usgs.gov) and a summary of the eruption is available in this “Volcano Watch” article: Volcano Watch — A New Kīlauea Eruption | U.S. Geological Survey (usgs.gov). 

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

 Hazards:  Near the recent middle East Rift Zone eruption site, minor to severe ground fractures and subsidence features may continue to widen and offset, may have unstable overhanging edges, and should be avoided. Hazards associated with the recent lava flows include glassy (sharp) surfaces that can cause serious abrasions, and lacerations upon contact with unprotected or exposed skin; uneven and rough terrain that can lead to falls and other injuries; or, locally elevated levels of volcanic gases that can lead to breathing difficulty.   

 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.