Helicopter overflight view of episode 16 lava fountain and its lava flow on the crater floor of Kaluapele at around noon on April 1, 2025. The lava flow at this time had traveled 2,300 ft (700 m) from the fountain along the floor of Halemaʻumaʻu. USGS photo by D. Downs.

Kīlauea summit lava fountain from the west end of Halemaʻumaʻu and the tephra blanket it has produced through its 16 episodes. In some places, the tephra blanket reaches more than 5 ft (1.5 m) thick. Most of the tephra from episode 16 lava fountain on April 1, 2025, was blowing to the northwest, with some clasts reaching Highway 11. USGS photo by D. Downs.

USGS Hawaiian Volcano Observatory geologist captured this aerial view during a monitoring helicopter overflight of episode 16 at around noon on April 1, 2025.  The lava fountain feeds a lava flow from the western end of Halemaʻumaʻu. This lava fountain reached heights of more than 650 ft (200 m) high and was blanketing the western part of the summit to Highway 11 with tephra clasts. Clasts were larger closer to the fountain. USGS photo by D. Downs.

On April 1, lava fountains from Kīlauea's ongoing summit eruption prevented geologists from accessing the rim of Halemaʻumaʻu crater within the closed portion of Hawaiʻi Volcanoes National Park. Instead, they hung back along the closed portion of Crater Rim Drive to collect samples of tephra that was intermittently blown in their direction. Here, a USGS Hawaiian Volcano Observatory geologist watches over the tephra fallout zone from the eruption, waiting for wind conditions to permit sample collection. USGS photo by M. Zoeller.

On April 1, a USGS Hawaiian Volcano Observatory geologist captured this zoomed-in photo of the upper portion of the active lava fountain during Kīlauea's ongoing summit eruption. Here, one can see the origin of tephra that has blanketed areas downwind of the eruptive vents during this eruption: while molten spatter (red) falls quickly back to earth, solid but frothy pieces of lava (black) loft higher in the plume, buoyed by hot gases escaping the eruptive vent. USGS photo by M. Zoeller. 

Late in the evening on April 1, USGS Hawaiian Volcano Observatory geologists watched the ongoing Kīlauea summit eruption from Kūpinaʻi Pali (Waldron Ledge). This view of the active eruptive vents was captured through the lens of a laser rangefinder device the geologists were using to measure lava fountain heights. USGS photo by M. Zoeller. 

Episode 16 lava fountains were visible from Highway 11 in Kaʻū on April 1. In this view, the top of the lava fountain is just visible above Halemaʻumaʻu crater rim, and Uēkahuna (the highest part of the caldera rim) is visible to the left. USGS photo by K. Mulliken. 

The episode 16 eruption plume was transported north-northwest on April 1, over Highway 11 in Kaʻū. USGS Hawaiian Volcano Observatory volcanic gas specialists traversed under the plume on the highway in order to get a sulfur dioxide emission rate for episode 16. Based on six traverses, they obtained an average emission rate of 50,000 tonnes per day of sulfur dioxide, which is in line with other measurements and emission rate estimates for other recent eruption episodes at Kīlauea summit. USGS photo by K. Mulliken. 

Episode 16 lava fountains deposited tephra and Pele's Hair on Highway 11 in Kaʻū on April 1. In this photo, taken around 3:30 p.m. HST, the tephra and Pele's Hair is visible along the centerline and on the shoulder of the highway. USGS photo by K. Mulliken. 

Wind conditions during episode 16 of the Kīlauea summit eruption resulted in material from the lava fountains being deposited on Highway 11 on April 1. This photo shows the amount of material, including tephra and Pele's Hair, that had accumulated by 3:30 p.m. HST. A Hawaii County Civil Defense Agency message at 12:49 p.m. HST stated, "If you are in this area, please do not stop, do not get out of your vehicle, and keep your window fully rolled up." USGS photo by K. Mulliken.