USGS Volcano Notice - DOI-USGS-HVO-2025-04-02T17:46:51+00:00

Activity Summary:  

Episode 16 of the ongoing Halemaʻumaʻu eruption is continuing but lava fountains have diminished significantly this morning.  Fountains this morning are less than 300 feet (90 m) high, significantly reduced from yesterday's heights of over 600 feet (180 m).  This drop in fountain intensity suggests that episode 16 may end soon.    

Kīlauea's current eruption in Halemaʻumaʻu crater within Kaluapele (the summit caldera) began on December 23, 2024. There have now been 16 episodes of various degrees of 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) and tephra that have impacted Hawai’i Volcanoes National Park and nearby communities.

Summit Observations:

The south vent began low level fountaining before 8 a.m. HST yesterday, April 1, and continued to increase until 10:24 a.m. HST when high fountaining began. South vent fountains grew rapidly in height and within 30 minutes they were over 600 feet (180 meters).  The south vent sustained high fountains averaging 600-800 feet (180-245 meters) over the next day.  The north vent continued lower-level activity yesterday, consisting of low fountaining and lava pond activity, until 9:22 p.m. HST April 1 when it shut down.  This morning, the south vent fountain height has dropped significantly, to less than 300 feet (90 m) beginning around 9:50 a.m. HST.  Additional details about the eruption were posted earlier in the Status Report and the April 1 Daily Update for Kīlauea.

The UWD tiltmeter recorded about 14 microradians of deflation thus far during episode 16, with just under 11 microradians lost on the SDH tiltmeter. Deflation rate was constant throughout the first part of the eruption reflecting the stable nature of activity from the south and north vents.  The deflation rate slowed slightly after the north vent shut down last night.  

Volcanic gas emissions remain elevated. Yesterday during high fountaining, SO₂ emission rates were measured at 50,000 tonnes per day along Highway 11 just northwest of Halemaʻumaʻu crater.  Currently, winds at the summit are forecast to be weak, which has allowed the plume of gas to spread around the summit region of Kīlauea. In addition, visitors to Hawaiʻi Volcanoes National Park and residents of adjacent areas may be exposed to Peleʻs hair and other small fragments of volcanic glass and tephra being carried in the plume, as they were during episode 15.  Yesterday about 0.5 inches or 1 centimeter of small pumice, ash, and Peleʻs hair fell on Highway 11.

Strands of volcanic glass known as Pele’s Hair from previous episodes are still present throughout the summit area of Hawai’i Volcanoes National Park and surrounding communities and can be remobilzed by wind if present. 

• 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.

Analysis: 

The current eruption has been characterized 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. Each of the previous 15 fountaining episodes lasted from a few hours to over a week and 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. A new probability window will be calculated when more data is available.

• 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 power system that supplies power to the KWcam webcamera, 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 webcameras are still functioning and online.

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 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

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.