Hawaiian Volcano Update: Kīlauea Summit Eruption’s Episode 17 - April 10, 2025
The 17th episode of Kīlauea’s ongoing summit eruption began on Monday night, April 7 at 10:15 pm, and lasted 35.5 hours until 9:45 am on Wednesday morning. Uniquely, episode 17 produced the shortest lava fountains with peaks around 200 feet or 60 meters since late January’s episode 7, breaking the pattern of growing lava fountains that ultimately reached over 1000 feet or 305 meters during episodes 15 & 16. Lava flows fed primarily from the south vent worked their way across Halemaʻumaʻu crater floor, covering about 40% of its surface according to the USGS-HVO. Ooze-up flows also reemerged from below the eastern crust as in previous episodes, following lava injection beneath the crater floor clearly visible in time-lapse sequence.
This past week, trade winds dominated during low fountaining, with reduced local impact of the eruption due to the combined effect of less tephra and Pele’s hairs escaping the caldera and winds blowing away from nearby communities. Gas emissions and erupted material carried by the wind remain the greatest threat to people on-island during this episodic eruption. Vog hazards are not new to island residents, and the usual precautions and preparations apply, especially for those with respiratory sensitivities – more information at https://vog.ivhhn.org/.
The onset of low fountaining during episode 17 immediately produced deflation on ground-tilt monitors at the summit unlike previous sequences, when deflation accompanied the high fountaining phase. In other words, during the ramp-up low level activity consisting of spattering and gas pistoning, the volcano had continued to inflate in previous episodes; thus, when deflation was immediately visible at the start of episode 17, it suggested some difference in the eruption to come, and indeed the high fountains did not manifest. The deflationary signal was also slower than during previous episodes, likely due to the reduced output rate also evidenced by lower fountains. Once the episode ended, the usual inflation signal resumed as the volcano appears to be recharging for its next event. According to the USGS-HVO, “preliminary data suggest that episode 18 is likely to begin in the next 5-8 days.”
As a special educational bonus this week, for the sake of comparison we present two other low-fountain episodes amidst a high fountaining sequence: Maunaulu’s episode 10 in October 1969, and Puʻuʻōʻō’s episode 19 in May 1984. In both cases higher fountaining resumed in later episodes, but there are also cases in which fountaining decreased prior to a change or end in activity.
Maunaloa continues to inflate quietly its established post-eruption pattern, 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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