USGS Volcano Notice - DOI-USGS-HVO-2025-03-26T18:29:05+00:00

Activity Summary:  

Episode 15 of the ongoing Halemaʻumaʻu eruption at Kīlauea's summit began at 12:04 p.m. yesterday, March 25, with cyclic lava spatter and flows from both the north and south vents. The cyclic behavior (“gas pistoning”) continues this morning. High fountaining is expected to follow this period of gas pistoning, as occurred during the previous episode.

NEW STREAMING WEBCAMERA:  The Hawaiian Volcano Observatory and Hawai'i Volcanoes National Park have worked together to install a new webcam (V2cam) with a view from the northeast rim of the caldera looking west towards the eruptive vents. This will provide a live view of the current eruption from a different angle compared to the existing livestream V1 cam. Like V1, V2 is a pan-tilt-zoom model and the view may change depending on activity.

Kīlauea's current eruption in Halemaʻumaʻu crater within Kaluapele (the summit caldera) began on December 23, 2024. There have been 15 episodes of lava fountaining separated by pauses in activity. All eruptive activity remains within Hawai'i Volcanoes National Park. No significant activity has been noted along Kīlauea’s East Rift Zone or Southwest Rift Zone.

Current hazards include volcanic gas emissions and windblown volcanic glass (Pele’s Hair) that may impact Hawai’i Volcanoes National Park and nearby communities.

Summit Observations:

Episode 15 was preceded by eight cycles of lava rise and small spatter fountains in the north vent, which lasted for 5-10 minutes each and began at approximately 9:27, 9:55, 10:11, 10:29, 10:48, 11:07, 11:27, and 11:45 a.m. HST on March 25. These cycles are a phenomenon known as “gas pistoning”, which has been observed in other eruptions at Kīlauea in recent decades. The onset of Episode 15 at 12:04 p.m. HST was marked by the start of more dynamic gas pistoning cycles, with vigorous dome fountaining that fed overflows from the north vent onto the floor of Halemaʻumaʻu crater.  Dome fountains 30-60 feet (10-20 m) high and vent overflows were then always followed by rapid drainback and coincident drop in the level of the lava pond within the north vent.  A slow refilling and rise in the level of the pond marked the onset of each new cycle. The south vent was also intermittently active during this time and fed a smaller set of lava flows.  This activity continues mostly unchanged as of this update, although the south vent flows have grown larger at times. Flows from both vents have covered less than 20% of the floor of Halemaʻumaʻu crater as of this update. Overall, there have been close to 100 gas piston cycles so far in this episode.

The UWD tiltmeter experienced instrument malfunction on Friday March 21 and was repaired yesterday. At this time, UWD tilt is generally flat, while SDH tilt continues to increase. Inflationary tilt at SDH reached just over 6 microradians since the end of the last episode, recovering more than 100% of the tilt lost from episode 14. Seismic tremor began increasing and decreasing with the cyclic fountains and drainback. 

Volcanic gas emissions remain elevated. A maximum sulfur dioxide (SO₂) emission rate measured in the morning on March 20 reached approximately 50,000 t/d, and similar levels of gas emission are expected for any high fountaining associated with Episode 15. Based on prior measurements, average SO₂ emission rates during cyclic gas pistoning are likely to be slightly elevated (approximately 2,000 t/d) as compared to during inter-episode pauses (approximately 1,000 t/d).

Strands of volcanic glass known as Pele’s Hair have been reported on surfaces throughout the summit area of Hawai’i Volcanoes National Park and surrounding communities. 

• Summit eruption livestreams: Kīlauea Volcano, Hawaii (West Halemaʻumaʻu crater) v1cam and the NEW Kīlauea Volcano, Hawaii (East Halemaʻumaʻu crater)v2cam

• Summit eruption webcams: https://www.usgs.gov/volcanoes/kilauea/summit-webcams 

   

Rift Zone Observations:

Rates of seismicity and ground deformation remain very low in the East Rift Zone and Southwest Rift Zone with no significant earthquake activity in the past 24 hours. Sulfur dioxide (SO₂) emissions from the East Rift Zone remain below detection limit.

Analysis: 

The current eruption is marked by episodic fountaining not seen in any of the other Halemaʻumaʻu eruptions since 2020. Fountains and lava flows have erupted from two vents that we refer to as the north vent and south vent. The 14 earlier fountaining episodes lasted from a few hours to over a week. Each fountaining episode has been accompanied by strong deflation of the summit region. Pauses between the fountaining episodes have been marked by an immediate change from deflation to inflation as the magma chamber recharges and repressurizes.

Analysis of inflationary tilt patterns prior to the onset of each fountaining episode allows a time window of probability for the onset of new episodes to be estimated. These are calculated using both minimum inflation necessary to start a new eruption and the rate of inflation fit to data derived from past eruptive episodes. Episode 15 began yesterday within the expected window of time, albeit with cyclic gas pistoning and lava overflows from the vent rather than an immediate return to high fountaining. Based on similar behavior during episode 14, we expect that gas pistoning will transition to high lava fountaining today, March 26. General eruptive behavior and timing for this episode, as well as the degree of deflation during the activity, will dictate forecasts and expectations for activity beyond the current episode.

• Timeline of eruptive episodes since December 23, 2024: https://www.usgs.gov/volcanoes/kilauea/science/eruption-information
• Summit eruption reference map: January 15, 2025—Kīlauea summit eruption reference map | U.S. Geological Survey
• Volcano Watch article about Pele's Hair from this eruption: https://www.usgs.gov/observatories/hvo/news/volcano-watch-recent-lava-fountains-highlight-peles-hair-hazards

HVO continues to closely monitor Kīlauea and is in contact with Hawai‘i Volcanoes National Park and the Hawai‘i County Civil Defense Agency about eruptive hazards.

Please see the Hawaiʻi Volcanoes National Park website for visitor information: https://www.nps.gov/havo/index.htm.

General Updates: 

The Hawaiian Volcano Observatory and Hawai'i Volcanoes National Park have worked together to install a new webcam (V2cam) with a view from the northeast rim of the caldera looking west towards the eruptive vents. This will provide a live view of the current eruption from a different angle compared to the existing livestream V1 cam. Like V1, V2 is a pan-tilt-zoom model and the view may change depending on activity.

Hazards: 

This episodic eruption is occurring within a closed area of Hawai'i Volcanoes National Park. High levels of volcanic gas—primarily water vapor (H₂O), carbon dioxide (CO₂), and sulfur dioxide (SO₂)—are the primary hazard of concern, as this hazard can have far-reaching effects downwind. As SO₂ is continuously released from the summit during an eruption, it will react in the atmosphere to create the visible haze known as vog (volcanic smog) downwind of Kīlauea. SO₂ and vog may cause respiratory and other problems at high concentrations. Further information on vog can be found at https://vog.ivhhn.org/

Additional hazards include Pele's hair and other volcanic fragments from lava fountains. Pele's hair are strands of volcanic glass often produced by lava fountaining activity. Volcanic fragments can fall on the ground within a few hundred yards (meters) of the eruptive vent(s), or on the western caldera rim downwind of the vent(s). Strong winds may waft light particles to greater distances downwind. Once they are on the ground, they can sometimes cluster and tangle together giving it the appearance of a tumbleweed. The extent of Pele's hair is dependent on lava fountaining activity and current wind conditions.  Residents and visitors should minimize exposure to these volcanic particles, which can cause skin and eye irritation. More information about how Pele's hair is formed is available here: https://www.usgs.gov/observatories/hvo/news/volcano-watch-peles-hairs-a-beautiful-hazard-island-hawaii. A Frequently Asked Questions document developed for the 2022 Mauna Loa eruption includes information about potential health effects of Pele's hair and is available here: https://vog.ivhhn.org/sites/default/files/FAQ_on_air_quality_and_health_during_Mauna_Loa_eruption_v1.6.pdf

Hawaiian lava flows generally advance slowly downslope, and during this eruption flows have been confined to Halemaʻumaʻu crater and the southwest side of Kaluapele, Kīlauea's summit caldera. 

Other significant hazards also 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 Kīlauea's caldera rim surrounding Halemaʻumaʻu crater, an area that has been closed to the public since late 2007.

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