Hawaiian Volcano Update: Kīlauea Summit Eruption’s Episode 18 Fountains - April 24, 2025

Kīlauea erupted its 18th episode of lava fountaining during Merrie Monarch week this past Tuesday, April 22nd, peaking at heights of roughly 650 feet or 200 meters over 10 hours from 3:30 am to 1:28 pm. Weak and variable winds contributed to the fallout of tephra and Pele’s hairs within Hawaiʻi Volcanoes National Park, prompting closures in the Uēkahuna area, as well as impacting nearby Volcano Village. 5 million cubic meters of lava erupting at 140 cubic meters per second fed flows that covered 60% of the Halemaʻumaʻu crater floor, favoring the southern crater wall this time unlike many recent episodes. Another webcam operated by the USGS Hawaiian Volcano Observatory was unfortunately put out of comission by these flows, adding to the maintenance list that already constituted two other webcams and a laser rangefinder impacted by the high fountains of episode 15.

Changing the pattern once again, the main fountaining phase of episode 18 followed a full 5 days after the first overflows of lava late the previous Wednesday night, marking the longest precursory activity of any episode and the longest total duration since episode 3. This was paired with a shorter-than-average duration of vigorous eruption, but given that episode 17 lacked fountains exceeding 200 feet or 60 meters, episode 18’s taller fountains can be seen as a return to the previous norm. After the first precursory overflow on Wednesday night April 16, another set of 4 overflows erupted on Sunday night April 20, before the final cycle began early on April 22. 

As with previous episodes, ground monitoring signals and continuing glow from the vents suggests the volcano is recharging once again such that another episode seems likely. However, the variability evident in the past couple of episodes raises a little more doubt as to what could happen or change next. According to the USGS-HVO, “preliminary data indicate that episode 19 may start sometime within the next one to two weeks. As more data becomes available, the window will be adjusted.”

Maunaloa continues to inflate quietly its established post-eruption pattern, perhaps even a little more quietly over the past two months, with only small-magnitude earthquakes and minor adjustments evident on monitoring instruments. As usual, we summarize the monitoring signals, imagery, and reports for both volcanoes available courtesy of the USGS Hawaiian Volcano Observatory, annotating the presentation on screen as we go and discussing live viewer questions. 

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