Dual lava fountains from Kīlauea’s Halemaʻumaʻu crater reach 400 m (1 300 feet), Hawaii
Episode 34 of the ongoing Kīlauea eruption ended at 07:03 HST (17:03 UTC) on October 1, 2025, after 6 hours of lava fountaining from two vents in Halemaʻumaʻu crater at the volcano’s summit, Hawaii. Lava fountains reached up to 400 m (1 300 feet), erupting about 9 million m³ (12 million yd³) of lava at a peak effusion rate of 382 m³/s (500 yd³/s). The eruption filled much of the western crater floor before activity ceased.
Eruption at Kilauea volcano at 05:55 HST on October 1, 2025. Credit: USGS/HVO
Kīlauea’s episode 34 eruption ended at 07:03 HST (17:03 UTC) on October 1, after approximately 6 hours of lava fountaining from two vents within Halemaʻumaʻu crater at the volcano’s summit.
The U.S. Geological Survey (USGS) Hawaiian Volcano Observatory (HVO) reports that lava fountains reached 100 m (330 feet) from the north vent and up to 400 m (1 300 feet) from the south vent.
The two vents produced high-volume channelized lava flows that covered much of the western crater floor. The erupted volume is estimated at 9 million m³ (12 million yd³), equivalent to about 2.5 billion gallons of lava. Effusion rates peaked at about 382 m³/s (500 yd³/s), nearly double those recorded in previous episodes of the current eruption sequence.
Ground deformation during the eruption included 26 microradians of deflationary tilt, consistent with rapid magma withdrawal from the summit reservoir. Since activity ceased, tiltmeters have recorded a return to inflation, suggesting magma recharge. HVO notes that another fountaining episode is likely but not expected for at least a week.
Gas emissions remain elevated, with sulfur dioxide output typically ranging between 1 200 and 1 500 t/day during pauses. Vog (volcanic smog) produced from SO2 emissions continues to affect areas downwind of the summit.
The eruption also produced significant quantities of Pele’s hair, strands of volcanic glass that can travel more than 15 km (10 miles) from the vent. The fibers, along with other tephra such as pumice and scoria, have been reported across the summit region and along Highway 11, depending on wind conditions.
Pele’s hair poses hazards of skin and eye irritation and contamination of catchment water supplies, and may be remobilized by wind even after eruptive activity ends.
The eruption has remained confined to Halemaʻumaʻu crater, inside the closed area of Hawai‘i Volcanoes National Park. However, hazards persist around the caldera rim, including unstable crater walls, ground cracking, and rockfalls.
Seismicity and deformation remain low in Kīlauea’s East and Southwest Rift Zones, and sulfur dioxide emissions from those regions are below detection limits.
According to HVO, the episodic pattern of short, intense lava fountains has been ongoing since December 23, 2024, resembling the 1983–86 eruptive behavior of Puʻuʻōʻō. Each episode is marked by rapid summit deflation during fountaining, followed by inflation as the magma chamber repressurizes. On average, episodes have occurred about once per week.
The current Volcano Alert Level is WATCH, and the current Aviation Color Code is ORANGE. HVO continues to coordinate with Hawai‘i Volcanoes National Park and the Hawai‘i County Civil Defense Agency to monitor hazards and provide updates.
References:
1 HAWAIIAN VOLCANO OBSERVATORY DAILY UPDATE – USGS/HVO – October 1, 2025 at 19:46 UTC
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FYI —
Since the late afternoon of 16 Oct 2025 there have been numerous flows of lava – most visible on [V3 Cam]
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FYI – There was an ‘event’ on 4 Oct @ +/- 04:24:30 (HI Time) – It was ‘up-slope’ of the craters and visible to some extent on all 3 camera views.
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