Hawaiian Volcano Update: Kīlauea Summit Eruption’s Episode 11 - February 27, 2025
After a 5-day pause, Kīlauea resumed erupting at its summit from 6:26 pm Tuesday night, February 25th, to 7:06 am Wednesday morning, February 26th, lasting just uner 13 hours in total. Episode 11 was most notable for its lava fountains peaking around 600 feet or 180 meters high within the first 2 hours of the eruption, even as flows covered up to 80% of the base of Halemaʻumaʻu crater. “Large amounts of pumice, Pele’s hair, and lightweight reticulite were deposited up on the west rim” along with “‘ribbon’ bombs up to about 1-2 feet (0.3-0.6 meters) … found on top of the pumice.” The north vent was the first to both start and stop erupting, with the south vent following about half an hour later each time. Curiously, last night “strong intermittent glow was present at the south vent, but the north vent remained uncharacteristically dark” according to the USGS Hawaiian Volcano Observatory.
The night before, glow was noted from the area of the September 2023 cones on the down-dropped block within the crater, suggesting “that magma within the vent system may have intruded into the molten interior of Halemaʻumaʻu prior to the onset of episode 11. Similar glow was not observed along the 2023 vents prior to or during episode 10.” After the vents quieted ending episode 11, lava flows continue to erupt in the northeast part of Halemaʻumaʻu “that appear to have been emplaced from beneath the crater floor rather than from the recent flows.” Other breakouts are also occurring from the main episode 11 flow, as well as large crustal overturning events where the lava is thickly ponded, buoyant, and fluid.
Since the episode ended, the volcano shows the same evidence of recharge on monitoring signals seen during previous pauses. Based on the inflation rate over the first 24 hours of this pause, the USGS-HVO considers “that the most likely start of the next episode will come in the next 5-10 days, between Tuesday March 4 and Sunday March 9 depending on inflation rates at the summit.” Consistent with the present expectation, the most recent 4 episodes were followed by pauses of 6, 6, 7, and 5 days regardless of eruption duration ranging from 13 to 23 hours.
Similar to episodes 9 & 10, the trade winds appear to have caught the gas emissions from episode 11 and carried them on their usual route over Kaʻū toward the south Kona coast and offshore, with reductions in air quality in that area evident on the PurpleAir network again this week. Episode 11 also ties episodes 6 and 10 for the shortest duration lava fountains thus far, limiting the high-volume output from the volcano and largely sparing the Hilo side of the island from the initial outburst of vog once again. However, changing winds in the next days may remobilize existing emissions to affect much of Hawaiʻi Island, based on the Vog Measurement and Prediction Project forecast.
SO2 emissions rates are estimated around 10,000 tonnes per day during eruptions and around 1,000 tonnes per day during the pauses, a significant increase above our already high (for people) background emission levels. During the pause just after the end of episode 10, emissions were measured at 2,100 tonnes per day. Thus the vog may continue to pose the greatest hazard to people, especially those with respiratory sensitivities. Higher lava fountains also bring the continued hazard of Pele’s hairs for nearby viewers and communities. Vog hazards are not new to island residents, and the usual precautions and preparations apply – more information at https://vog.ivhhn.org/.
The ongoing summit eruption, even with its episodes and pauses, continues to relieve stresses on Kīlauea’s rift zones, which have remained relatively quiet with no major seismicity or ground deformation since more than a week before the current eruption. The volcano’s south flank still shows background seismicity highlighted by a magnitude 3.1 early today, as well as continuing deep quakes in the Pāhala sector.
Maunaloa continues to inflate quietly its established post-eruption pattern, with only 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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