Hawaiian Volcano Update: Kīlauea Summit Eruption’s Episode 16 - April 3, 2025
Another week, another burst of fountaining at Kīlauea’s summit, this the 16th episode of the current eruption which began 100 days prior on December 23, 2024. The north vent began to erupt with spattering and low fountaining around 6 pm on Monday, March 31, before lava spilled from the vent around 11pm marking the start of the episode. At 8 am the following morning, the south vent joined in with low level activity, transitioning to high lava fountains at 10:24 am on Tuesday, April 1. After more than 25 hours of high fountains, and 37 hours overall, episode 16 ended at 12pm on Wednesday, April 2. According to the USGS Hawaiian Volcano Observatory, “the south vent sustained high fountains averaging 600-800 feet (180-245 meters)” over the day-long period, feeding lava flows that covered about 50% of Halema’uma’u crater floor.
Once again, variable winds during the high fountaining allowed tephra and Pele’s hairs to be carried into nearby communities and areas, including the county’s Highway 11 west of the summit in Ka’u which prompted a local alert. Gas emissions and erupted material carried by the wind remain the greatest threat to people on-island. 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 possibility of a prolonged onset following episode 15 and its subsequent vent blockages and summit earthquakes did not come to pass. Following episode 16, inflation and tremor have returned in the usual pattern similar to many prior episodes, such that another episode is expected. Given the larger than average discharge for this episode, a result of longer than average high fountains, the volcano deflated by a larger amount that will take longer to recover even at the current healthy rate of recharge. The USGS-HVO suggests “the onset of the next episode is most likely to be next Thursday to Sunday, 7 to 10 days from now,” although the outlook is adjusted daily based on additional incoming data. Following the previous 5 episodes, the average length of the pause between episodes is about 6 days. One unusual occurrence following the latest episode were small spattering events in the south vent after fountaining ended, and the deposits of bright yellow sulfur minerals on the vent cones evident this morning.
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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