Hawaiian Volcano Update: Episodes 40 & 39, Kīlauea Summit Eruption - January 15, 2026
Episode 40 of Kīlauea’s ongoing summit eruption lasted just under 10 hours this past Monday, January 12, from about 8:22 AM to 6:04 PM, fountaining up to 800 feet or 250 meters from only the north vent. Over the prior 4 days, precursory activity “included cyclic spatter and dome fountains from both the north and south vents that fed large lava flows on the crater floor including a flow from the south vent that reached 3,300 feet (1,000 meters) in length.” An estimated 5.5 million cubic meters of lava erupted, covering up to 60% of Halemaʻumaʻu crater floor with new flows. While impressive, this marks a reduction in volume and discharge rate from episode 39 despite a longer duration, likely due to the lack of fountaining from the south vent.
As activity increased on Monday morning, “the north vent appeared to have a constricted opening,” generating “an arcuate spatter fountain that grew in vigor dramatically at 8:13 AM.” Fountain heights peaked just before 10 AM, during which weak winds allowed the eruptive plume to rise “to over 13,000 feet (4,000 meters) above ground level before moving to southeast at higher altitudes.” Tephra fallout was noted on the western section of the caldera, “with reticulite as large as 2 inches (5 cm) falling at the Uēkahuna Overlook in Hawaiʻi Volcanoes National Park briefly” at that time. “Large whirlwinds or ʻpuahiohio’ also occurred during episode 40 and were visible in the livestreams.”
Since the end of episode 40, the volcano shows all the signs of recharging for an episode 41, through ground tilt, glow, and tremor, suggesting a preliminary window of January 19 to 25 for the next outburst. Both vents continue their typical inter-episode degassing of 1,000 to 5,000 tonnes of SO2 per day, which with weak winds are still sufficient to affect nearby communities. Vog and tephra remain the most common hazards for island residents, and the usual precautions and preparations apply, especially for those with respiratory sensitivities – more information at https://vog.ivhhn.org/.
Maunaloa continues its long-term post-eruption filling pattern, with the caldera slowly stretching and rising, accompanied by earthquakes. Over the past week, deeper earthquakes under the summit are making a return. As usual, we summarize the monitoring signals, imagery, and reports available courtesy of the USGS Hawaiian Volcano Observatory, annotating the presentation on screen as we go and discussing live viewer questions.
