USGS Volcano Notice - DOI-USGS-HVO-2025-04-20T19:33:50+00:00

Activity Summary:

Episode 18 of the ongoing Halemaʻumaʻu eruption resumed with lava overflowing the south vent at 3:20 a.m. HST on April 22 followed by the onset of fountaining from both vents at 3:30 a.m. HST. Lava began overflowing the north vent at 3:47 a.m. HST. Fountains are currently over 650 feet (200 meters) high at the south vent and over 160 feet (50 meters) at the north vent. Both fountains are feeding a vigorous flow on the floor of Halemaʻumaʻu crater. Lava has currently covered about over 20% of the floor of Halemaʻumaʻu crater. Strong deflation accompanied the onset of lava flows at 3:20 a.m. and tremor increased with the onset of fountaining from both vents.

Prior to the onset of high fountaining, intermittent spattering began at the north vent around 1:30 a.m. HST and increased in frequency until 3:20 a.m. HST when lava began erupting. Additional information on the resumption of episode 18 can be found in the April 20 Kīlauea update and the April 21 Kīlauea update.

Kīlauea's current eruption in Halemaʻumaʻu crater within Kaluapele (the summit caldera) began on December 23, 2024. There have now been 18 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.

Volcanic gas emissions remain elevated and at heightened levels due to lava fountaining. The last sulfur dioxide (SO₂) emission rate measured on April 10 was approximately 1,200 tonnes per day. Typical levels of Sulfur dioxide (SO₂) emission have been about 1,000 tonnes per day during previous pauses. Sulfur dioxide (SO₂) emission rates during earlier high fountaining episodes have reached 50,000 tonnes per day. This morning, the winds are slack and Pele's hair could fall throughout Hawaiʻi Volcanoes National Park and surrounding communities.

Strands of volcanic glass known as Pele’s hair can be produced by fountains and fall on the summit area of Hawaiʻi Volcanoes National Park and surrounding communities. Current wind directions are likely to carry most of the Peleʻs hair away from established viewing areas and communities.

• Timeline of eruption episodes since December 23, 2024: https://www.usgs.gov/volcanoes/kilauea/science/eruption-information 
• Two Kīlauea summit livestream videos are available here: Kīlauea Volcano, Hawaii (West Halemaʻumaʻu crater) v1cam and 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.

General Updates: 

• 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.

The power system that supplies power to the KWcam webcam, the F1cam thermal camera, and the laser rangefinder sustained damage during the high fountaining on March 26, 2025. Both cameras and the rangefinder are currently offline. Other HVO webcams are still functioning and online.

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, 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 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