USGS Volcano Notice - DOI-USGS-HVO-2025-08-08T17:49:40+00:00

Activity Summary:

Episode 30 of the ongoing Halemaʻumaʻu eruption ended abruptly at 12:55 p.m. HST on August 6 after 12 hours of continuous fountaining. Lava fountains reached up to 165 ft (50 m) and erupted lava covering 80% of the crater floor during this episode.  A new fissure vent that transected the south wall of Halemaʻumaʻu ceased erupting at 4:40 a.m. HST on the morning of August 6. Volcanic gas emissions have greatly decreased. Models show that episode 31 could start sometime late next week or during the week afterwards.

Summit Observations:

The north vent remained incandescent on the night of August 6th but it gradually dimmed in the early morning hours of August 7.  No incandescence has been observed from the north vent or other vents since then.  Tremor patterns characteristic of gas pistoning of magma continue suggesting the lack of glow may be due to lava residing deep within the vent or the vent may have developed a shallow blockage. images from an overflight on Wednesday showed that episode 30 flows had covered nearly 80% the Halemaʻumaʻu crater floor, which now includes the old down dropped block.  Points of incandescence could be seen in the flow field and on the cone last night and may be visible for several more days. 

The Uēkahuna tiltmeter (UWD) recorded about 22.5 microradians of deflationary tilt during this episode. The end of the eruption was coincident with a rapid change from deflation to inflation at the summit and a decrease in seismic tremor intensity. The Uēkahuna tiltmeter (UWD) has recorded just over 5 microradians of inflationary tilt since the episode ended. Incandescence from the recent lava flows was visible last night,

Elevated degassing continues from the vent. Average sulfur dioxide (SO₂) emission rates during inter-episode pauses are typically 1,200 to 1,500 t/d, though emission rates vary on short time scales in association with gas pistoning.  

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 outside of the summit. Sulfur dioxide (SO₂) emissions from the East Rift Zone remain below the detection limit.

Analysis: 

The lack of glow from the north vent in the last day along with the large deflation during episode 30 suggest another long repose period before the onset of the next eruptive episode as was prior to episode 30.  Current inflation rates are high, but they tend to slow during the repose period.  Models show the possible onset of the next eruption either late next week to early in the week of August 19 or the week of August 19 depending on the model.  Changes in inflation rate will affect the models.  Periods of no inflation to negative inflation, as seen prior to episode 30, cannot be modeled and will delay the onset of the next episode.  

Another factor was the injection of a shallow dike resulting in a new southern fissure vent at the onset of episode 30.  This suggests that eruptive pressure continues to increase as the vent elevation gets higher and magma can be injected into weak areas of the surrounding summit.  It is possible this could result in permanent change in the vent locations and eruptive behavior.  Currently, there are no indications that any eruptive activity would occur outside of the summit region.  Kīlaueaʻs East Rift Zone continues to contract, indicating no magma is entering that part of the system.

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 Halemaʻumaʻu 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.