USGS Volcano Notice - DOI-USGS-HVO-2025-04-02T03:36:54+00:00

Activity Summary: 

Episode 16 of the ongoing Halemaʻumaʻu eruption ended at 12:03 p.m. HST on April 2 when high fountaining at the south vent stopped.  Fountains from the south vent sustained heights of 600-700 feet (180-210 meters) for over 23 hours, then dropped to less than 300 feet (90 meters) at 9:50 a.m. HST this morning, April 2.  Overall, episode 16 lasted just over 37 hours with the last 25 hours and 39 minutes consisting of fountains from the south vent. 

During episode 16, lava flows covered over 50% of the floor of Halemaʻumaʻu within the southern part of Kaluapele (Kīlauea caldera). Weak winds also resulted in deposition of Pele's hair and tephra in closed areas of Hawai'i Volcanoes National Park and on Highway 11 between mile marker 35 and 37 on April 1. Additional details about the eruption were posted earlier in the March 31 Status Report and the April 1 Status Report and the April 1 Daily Update for Kīlauea along with the April 2 Daily Update for Kīlauea.

The UWD tiltmeter recorded just over 14 microradians of deflation during episode 16, with 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 April 1 at 9:22 p.m. HST. The end of the eruption was coincident with a rapid change in tilt from deflation to inflation at the summit and a decrease in seismic tremor intensity when the fountains ceased at 12:03 p.m. HST. 

Each episode of Halemaʻumaʻu lava fountaining since December 23, 2024, has continued for at least 13 hours, and up to 8 days, and episodes have been separated by pauses in eruptive activity lasting less than 24 hours to 12 days. 

• 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

No changes have been detected in the East Rift Zone or Southwest Rift Zone. HVO continues to closely monitor Kīlauea and will issue an eruption update tomorrow morning unless there are significant changes before then. 

Kīlauea Volcano Alert Level/Aviation Color Code remain at WATCH/ORANGE. All current and recent activity is within Hawaiʻi Volcanoes National Park.

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 that can fall on the ground downwind of the eruptive vent(s). Pele's hair is strands of volcanic glass produced by lava fountaining activity. Strong winds may waft these light particles to greater distances downwind. Pele's hair can sometimes cluster and tangle together on the ground, 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 and the southwest side of Kaluapele, Kīlauea's summit caldera. 

Other significant hazards also remain around Kīlauea caldera from Halemaʻumaʻu 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, an area that has been closed to the public since late 2007.