USGS Volcano Notice - DOI-USGS-HVO-2025-03-31T18:45:51+00:00

Activity Summary:  

The summit eruption of Kīlauea, within Halemaʻumaʻu, is paused as of March 26, at 7:10 p.m. HST.  If the eruption continues, Wednesday, April 2, to Thursday, April 3, is the most likely window for the start of another episode. If the vent is partially blocked, additional pressure may be needed to clear the conduit, resulting in a delay of the next episode.

Summit inflation has increased after slowing yesterday, and once again appears similar to previous eruptive pauses. Minor tremor and vent glow have returned over the past 24 hours but remain weak and sporadic compared to previous eruptive pauses.

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) and tephra that have impacted Hawai’i Volcanoes National Park and nearby communities.

Summit Observations:

Episode 15 ended on March 26, 2025. Limited incandescent spots are still visible at night on the cones that host the eruptive vents and on the lava flows close to the vents. 

The condition of the vents after episode 15 appears substantially different than after the previous eruptive episodes. The south vent had initially maintained a small amount of nighttime glow after episode 15, but had gone dark two nights ago. Last night, minor, sporadic south vent glow returned. North vent has been dark since the end of episode 15. The lack of glow at the north vent is likely a result of episode 15 eruptive material blocking that vent. The resumption of glow at the south vent may indicate that magma is once again shallowing in the conduit. Overall, vent glow is substantially less than following previous episodes.

Tiltmeters at the summit recorded about 9 microradians of deflation at Uēkahuna (UWD) and 7 microradians of deflations at Sand Hill (SDH) during episode 15. Since the current pause began, UWD and SDH tiltmeters have each recorded just over 6.5 and 8 microradians of inflationary tilt, respectively. 

Immediately following the end of fountaining on March 26, seismic tremor decreased to near background. Intermittent tremor returned the following day (March 27), though at lower levels than during earlier pauses. Variably weak tremor had continued since then, including very low levels as of yesterday’s update. As of today, tremor has strengthened slightly but remains weak.

SO₂ emission rates during previous pauses were approximately 1,000 t/d but are likely less than that at this time. Wind conditions continue to prevent updated emission rate measurements.

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

• Additional information about episode 15 can be found in daily updates from March 26 and March 27, as well as in status reports from the onset of fountaining and the end of the episode
• 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 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.

The current pause is once again generally following the same pattern of reinflation as other pauses, after a short decrease in the rate of inflation ahead of yesterday’s update. Still, other observations have indicated some differences with this pause. The short increase in small earthquakes immediately following episode 15, the significant drop in tremor, and the diminished glow at the vents may indicate that the vents are blocked or that magma is no longer very shallow in the conduit system. Either of these situations could lead to the observed decrease in tremor. 

If the pattern of episodes continues irrespective of observed differences with this pause, the current rates of inflation indicate that a new episode could begin mid-week. The likely window for the start of episode 16, if it occurs, is between Tuesday, April 1, and Thursday, April 3, with Wednesday to Thursday most likely. However, if observed differences in monitoring data are indicative of significant changes to the conduit or magma plumbing system, the eruption re-start window could be delayed, or the eruption could end. Note that data from the SDH tiltmeter has diverged from that at UWD since episode 15 and is no longer being used to forecast probability windows.

• 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.