Six Months of Halemaʻumaʻu Lava Fountains — USGS Volcano Watch
There is much to appreciate about the ongoing Kīlauea summit eruption as it approaches its 6-month anniversary on June 23. The stunning episodic lava fountains and lava flows erupting within Halemaʻumaʻu crater in Hawaiʻi Volcanoes National Park have provided island residents and visitors with safe and accessible viewing opportunities. However, volcanic hazards are always present.
A cropped comparison of two USGS Hawaiian Volcano Observatory webcam images showing changes to the landscape of Kīlauea summit region over the past six months. Twenty-five episodes of lava fountaining within Halemaʻumaʻu have contributed to a growing deposit of tephra material in the closed area of Hawaiʻi Volcanoes National Park, southwest of the vents.
Respiratory irritants from the eruption, including volcanic gases and vog (volcanic smog), are affecting communities far downwind. Additionally, Pele’s hair (thin strands of volcanic glass) and tephra (volcanic rock fragments) ejected from the lava fountains are also carried downwind.
During trade wind conditions, tephra and Pele’s hair are blown to the southwest of Kaluapele, Kīlauea's summit caldera, in an area of Hawaiʻi Volcanoes National Park that has been closed to the public since shortly before the 2008–2018 summit eruption began. Tephra erupted during these typical wind conditions have formed a deposit that extends approximately 2 miles (3.5 kilometers) downwind of the vents, with smaller fragments and fine Pele’s hair traveling much further. The tephra has partially covered several volcano monitoring sites operated by the USGS Hawaiian Volcano Observatory (HVO), requiring field crews to remove tephra from solar panels and other infrastructure between episodes.
Episodes 23, 24, and 25 provided some of the most impressive fountaining seen to date, reaching heights of up to 1200 ft (365 m). These remarkable fountain heights deposited hills of tephra along the western rim of Halemaʻumaʻu crater that are estimated to be well over 50 ft (15 m) thick.
Aerial images comparing the tephra deposit southwest of Halemaʻumaʻu crater (left) from the ongoing eruption at Kīlauea summit. The top image, taken on December 27, 2024, during episode 3, shows a thin layer of tephra (brown) has already accumulated on the left side of the image. The bottom image from June 10, 2025, was taken the day before episode 25 high fountaining started, and a continuous tephra blanket is covering a wide section to the southwest of the caldera rim, and continuing out of view. The orange star marks the location of the north and south vents. The blue circle in the upper photo highlights a kīpuka of green trees, and in the lower photo shows the same location where the kīpuka has been covered by a thick layer of tephra. USGS photos.
During slack or Kona wind conditions, volcanic gases, tephra, and Pele’s hair are typically dispersed to the north and east of the crater, toward areas open to the public. Even during episodes with lower fountain heights of 330 ft (100 m) or less, like episodes 4 and 5, Pele’s hair was falling at visitor areas within Hawaiʻi Volcanoes National Park as well as Volcano Village and other nearby communities.
Episodes 15 and 16 had fountain heights over 1000 ft (300 m) tall, and episode 18 had fountain heights over 820 ft (250 m) tall. During these episodes tephra and Pele’s hair fell on Volcano House and the visitor center area, and as far away as Volcano Village and Mauna Loa Estates. The national park temporarily closed the area from Uēkahuna bluff to Kīlauea Overlook during episodes 15 and 18 due to the falling and wafting Pele’s hair and tephra. Tephra from episode 16 fell along a 2 mile (3.2 kilometer) stretch of Highway 11 in the Kaʻū District of the national park.
In addition to public viewing area closures within the national park during episode 15, tephra fallout also impacted a HVO volcano monitoring site on the western rim of Halemaʻumaʻu crater. The former site of the KWcam, F1cam thermal camera, and the laser rangefinder was mostly buried by tephra during that episode. This monitoring station was deployed in 2019, and recorded data through five previous Kīlauea summit eruptions since late 2020. This site’s infrastructure was removed after it received minor damage. The cameras and laser rangefinder are still functional and HVO is currently working to redeploy these monitoring instruments.
The B2cam on the down-dropped block was also moved due to impacts from the ongoing eruption. This site was relocated to the southern rim of Halemaʻumaʻu cater on April 29, after a channelized lava flow came within about 10–20 ft (3–6 m) of it. The camera housing melted from radiant heat from the lava, but the camera and the rest of the infrastructure remained intact and is now being used for HVO’s newest livestream camera: the V3cam.
In addition to impacting physical equipment, some of the highest lava fountains have even blocked the transmission of radio signals carrying HVO data streams. These temporary outages resulted from the high fountains blocking the line of sight for data telemetry between relay towers and monitoring stations located south and southwest of the summit. HVO staff are currently working to resolve this issue by redirecting signal paths.
The ongoing eruption may continue to produce lava fountain episodes that provide us with awe-inspiring views. Along with the spectacular activity, comes hazards as well as challenges to monitoring infrastructure and telemetry, which HVO staff are finding creative solutions to maintain.
—
Volcano Watch is a weekly article and activity update written by U.S. Geological Survey Hawaiian Volcano Observatory scientists and affiliates
