USGS Volcano Notice - DOI-USGS-HVO-2025-07-19T16:42:59+00:00

Activity Summary:

The ongoing eruption of Halemaʻumaʻu is paused. The end of lava fountaining episode 28 on July 9 coincided with the return of inflationary tilt at the summit, which continues at this time. Low-level seismic tremor, degassing, and vent glow persist, while inflationary tilt has surpassed the level recorded at the onset of episode 28. These observations indicate that episode 29 is near, and the current summit inflation level suggests it will likely occur sometime July 19 or 20 (today or tomorrow; see Analysis section).

No significant activity has been noted along the volcano's East Rift Zone or Southwest Rift Zone.

Current hazards include volcanic gas emissions, along with windblown volcanic glass (Pele’s hair) and tephra (ash and pumice) deposited during earlier eruptive episodes.

Summit Observations:

Last night, webcam views showed stronger glow at the north vent than previous nights, indicating that lava may be approaching the surface again. Additional incandescence remains visible in the crack system on the tephra cone just above the north vent.

Seismic tremor and degassing persist at lower levels compared to fountaining episodes, though both remain above background. A significant increase in north vent glow between 11:00 p.m. and 12:00 a.m. HST last night (July 18–19) was accompanied by a small, sustained increase in tremor. Typical sulfur dioxide (SO₂) emission rates associated with pause periods are 1,200 to 1,500 tonnes/day. Unlike many other recent pauses, gas pistoning has been minor thus far during this pause.

Lava fountaining associated with episode 28 resulted in 15 microradians of deflation on the UWD tiltmeter. At the time of this update, UWD shows about 16.8 microradians of re-inflation since the end of the episode.

Strands of volcanic glass known as Pele’s hair are present throughout the summit area of Hawaiʻi Volcanoes National Park and surrounding communities and can be remobilized by wind even after fountaining has ceased.

• 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 that show eruptive lava fountains are available here: https://www.youtube.com/@usgs/streams 
• Summit eruption webcams: https://www.usgs.gov/volcanoes/kilauea/summit-webcams
• Volcano Watch article on gas pistoning: https://www.usgs.gov/observatories/hvo/news/volcano-watch-so-what-earth-or-least-kilauea-a-gas-piston

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: 

Summit inflation has surpassed the deflation experienced during episode 28 on July 9. Forecasting models have been adjusted using the maximum inflation recorded in the past 15 episodes; the new models, coupled with the return of strong glow to the north vent last night, indicate that episode 29 will likely occur sometime July 19 or 20 (today or tomorrow). The blockage created by slumping of the tephra cone into the north vent at the end of the episode 28 appears to have been partially or completely removed last night, as indicated by the stronger glow and small increase in tremor.  

The current eruption has been characterized by episodic lava fountaining not seen in any eruptions since the 1983–86 episodic fountains at the beginning of the Puʻuʻōʻō eruption. Lava fountains and flows have erupted from two vents within Halema'um'a'u crater that we refer to as the north vent and south vent. Each of the previous fountaining episodes lasted from a few hours to over a week and was accompanied by strong deflation of the summit region. Pauses between the fountaining episodes have been marked by an immediate switch from deflation to inflation as the magma chamber recharges and repressurizes. Fountaining episodes have occurred approximately once per week since the start of the current eruption on December 23, 2024.

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 Hawai'i Volcanoes National Park. High levels of volcanic gas—primarily water vapor (H₂O), carbon dioxide (CO₂), and sulfur dioxide (SO₂)—are one major 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/.

Another major hazard is fallout of Pele's hair and other volcanic fragments from lava fountains. Pele's hair is strands of volcanic glass often produced by lava fountaining activity that can be carried well over 10 miles (15 kilometers) from the vent. Other hot glassy volcanic fragments (tephra) including volcanic ash, pumice, scoria, and reticulite can fall on the ground within 1-3 miles (1-5 kilometers) of the eruptive vent(s), with the highest concentrations immediately downwind of the vent(s). Various volcanic fragments have fallen on Highway 11 west of Hawai'i Volcanoes National Park at times, depending on wind and eruption conditions. Strong winds may waft light particles, including Pele's hair, to greater distances downwind. Once 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 wind conditions. Residents and visitors should minimize exposure to Pele's hair and other glassy volcanic fragments, which can cause skin and eye irritation and can also contaminate catchment water supplies. 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 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_v2.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.