Hawaiian Volcano Update: Kīlauea Summit Eruption’s Episode 18 Begins - April 17, 2025
After a one week pause, Kīlauea’s ongoing summit eruption began its 18th episode with a small pulse of lava last night, Wednesday April 16 at 10:01 pm. The north vent began glowing strongly again on Monday night, when even occasional spatter was reported after several days of darkness. The south vent has been glowing more consistently since the end of episode 17, intensifying over time. However, last night it was the north vent that began spattering around 9:10 pm, building to 15-feet or 5-meter tall dome fountains around 9:30 pm, with the lava pond rising into sight by 9:45 pm, and spilling roughly 100 yards or meters onto the Halemaʻumaʻu crater floor between 10 pm and 11:21 pm, when this first pulse of activity ended.
Unlike episode 17, when the ground began deflating with the onset of low fountaining, the current monitoring signals show continued inflation of the volcano across the brief pulse of lava last night, suggesting further activity is imminent. Once steep deflation is evident on the data monitors, the countdown to the end of the episode is on. The prior 4 episodes have averaged roughly 33 hours in duration from when lava first spills outside the vent, with the first 3 of those averaging 21 hours of build-up before the onset of higher fountains. The last episode never reached that phase despite erupting for 35.5 hours.
In the past couple of days, winds have shown some variability beyond the dominant trade winds, with gas and tephra emissions from the volcano potentially likely to impact nearby communities. Vog hazards and by now tephra fallout 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/.
As a special educational bonus this week, we take a closer look at the episodic lava fountain heights of the 1959 Kīlauea Iki eruption including the record 1,900-foot or 580-meter high fountain, and consider how that might affect the impacts on nearby communities were it to peak similarly today. In the end, that height was sustained for only a few minutes before the fountains decreased to a maximum of 700 feet or 215 meters for the remaining hour and a half.
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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