Activity Summary:

Episode 22 ended at 03:29 p.m. HST on Friday, May 16, 2025 after 10 hours and 16 minutes of sustained fountaining from the north vent. The Halema‘uma‘u eruption is currently paused.

Activity levels overnight were subdued with intermittent incandescence from the active north and south vents. Night-time incandescence from episode 22 lava deposits was visible near the active vent region and along the northern margin of Halema‘uma‘u crater. 

Kīlauea's current eruption in Halemaʻumaʻu crater within Kaluapele (the summit caldera) began on December 23, 2024. There have now been 22 episodes separated by pauses in activity. All eruptive activity remains within Hawaiʻi 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) and tephra that have impacted Hawaiʻi Volcanoes National Park and nearby communities.

Summit Observations:

Episode 22 was preceded by small, sporadic gas-piston events that produced spatter fountains and short lava flows that began at 10:45 p.m. HST on May 15. Five more gas-piston overflows occurred in the early morning of May 16 (00:30; 1:00; 1:25; 1:54; 2:43 a.m. HST) until 4:40 a.m. when dome fountains overflowed the vent. By 5:13 sustained high fountaining began. Sustained fountains from the north vent peaked at 800-1000 feet (200-300 meters) high around 6:00 a.m. HST and began to oscillate in height around 328-492 feet (100-150 meters) after this time.  Fountains fed multiple lava streams. Lava flows from this episode covered up to 40% of the floor of Halemaʻumaʻu within Kaluapele (Kīlauea caldera). The estimated volume of erupted lava is 3.8 million cubic meters (5 million cubic yards).

The tiltmeter at Uēkahuna (UWD) recorded 10.3 microradians of deflation during episode 22. Tilt rapidly switched to inflation at 3:29 p.m. HST on May 16. This morning, UWD has recorded approximately 2.2 microradians of inflationary tilt since the end of episode 22.

Sulfur dioxide (SO₂) emission rates this morning are expected to be similar to rates recorded during prior pauses around 1,200 tonnes per day (t/d).

Strands of volcanic glass known as Pele’s hair from previous episodes are still present throughout the summit area of Hawaiʻi Volcanoes National Park and surrounding communities and can be remobilized by wind.

• Eruption resources, including the most recent map and a timeline of eruption episodes since December 23, 2024: https://www.usgs.gov/volcanoes/kilauea/science/eruption-information 
• Three Kīlauea summit livestream videos are available here: Kīlauea Volcano, Hawaii (West Halemaʻumaʻu crater) v1cam, Kīlauea Volcano, Hawaii (East Halemaʻumaʻu crater) v2cam, and Kīlauea volcano, Hawaii (South Halemaʻumaʻu crater) v3 cam
• Summit eruption webcams: https://www.usgs.gov/volcanoes/kilauea/summit-webcams 

The B2, KW, and F1 summit webcams are currently offline due to eruption impacts. Other HVO summit webcams are functioning and online.

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 the detection limit.

Analysis: 

The current eruption has been characterized by episodic fountaining not seen in any eruptions since the 1983-86 episodic fountains at the beginning of the Puʻuʻōʻō eruption. Fountains and lava flows have erupted from two vents that we refer to as the north vent and south vent. Each of the previous 21 fountaining episodes lasted from a few hours to over a week and have 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.

The rapid rebound of recorded UWD and SDH tilt from deflation to inflation at the end of episode 22 along with strong glow overnight indicates that magma remains shallow in both the north and south conduits. Preliminary data indicate that episode 23 may be likely by the end of next week or early the following week, approximately 5-10 days from now.  A better estimate will be made when there is more data.  

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.

Hazards: 

This episodic eruption is occurring within a closed area of Hawaiʻi 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 is 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 downwind of the vent(s). Strong winds may waft light particles, including Pele's hair, to greater distances downwind. Once they are on the ground, Pele's hair can sometimes cluster and tangle together, giving it the appearance of a tumbleweed. The extent of Pele's hair deposition is dependent on lava fountaining activity and current wind conditions. Residents and visitors should minimize exposure to Pele's hair and other volcanic fragments, which can cause skin and eye irritation. More information about how Pele's hair forms, its hazards, and what to do is available here: https://www.usgs.gov/observatories/hvo/news/volcano-watch-recent-lava-fountains-highlight-peles-hair-hazards. A recently updated Frequently Asked Questions document that includes information about potential health effects of Pele's hair is available here: https://vog.ivhhn.org/sites/default/files/PelesHair_FAQs.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.