Hawaiian Volcano Update: Kīlauea Eruption’s New Vents, Broken Pattern - September 17, 2026
Following 7 days of precursory activity, Kīlauea oozed a relatively small amount of lava from 6 new vents just north of the existing vent complex at its summit on Monday, September 14 with the first vent appearing at 8:36 PM. Vents 2 & 3 opened the same night (8:46 & 10:20 PM), vent 4 on Tuesday morning (8:52 AM), vent 5 on Tuesday evening (8:58 PM), and vent 6 on Wednesday evening (5 PM). While this activity appears to break the pattern of lava fountains, it is not so easy to dismiss their return. During the Puʻuʻōʻō high fountaining era, 10 distinct episodes were associated with brief fissure or satellite-vent outbreaks, only the last of which brought about a change in the eruption.
Lava began overflowing from the north vent back on Monday, September 7, producing 104 lava flows through Saturday, September 12. The pattern changed on Sunday, September 13, following 3 days of increased earthquakes around the summit, after which the north vent switched to producing significant spatter which over the past 4 days has built a ~40-foot or 12 meter tall cone over the vent. At the same time, inflation slowed significantly coincident with an earthquake swarm beneath the location of the future vents. This suggests that magma broke its way into a new pathway during that period, working its way through it over the next 24 hours before emerging from vent 1. It also implies that the previous tilt threshold for fountaining onset in episode 54 is no longer valid for episode 55, as the surrounding rock holding in the prior pressure has cracked.
Based on prior occurrences at Puʻu’ōʻō, there are 2 favored possibilities for the eruption to take from here according to the USGS Hawaiian Volcano Observatory. First, the eruption could return to fountaining, repairing its conduit system through continued emplacement of lava. Second, the eruption could become continuous at the new vents, switching the style of the eruption in the long term. Other less likely possibilities include the formation of other, new vents in the summit region, or intrusion into the upper parts of the Southwest Rift or the East Rift. However, there is no sign of any activity in either rift zone or of any recent connection to the summit eruption. The USGS notes that east rift tiltmeters “show typical rainfall excursions early this morning. These changes are not related to magma movement.”
Interestingly, the new vents formed without much localized seismicity and without a large outburst of gas which typically accompanies the start of an episode. Dome fountains remained very low, with little to no tephra produced, such that no significant additional hazards were generated by this week’s excursion. However, another fountaining phase is still possible in the days or weeks ahead, so the risk of impact to neighboring communities still remains. Weak trades or variable winds are certainly possible as our unstable weather season continues, such that impacts may occur depending on the timing. Between episodes, the vents continue to emit roughly 1,000 to 5,000 tonnes of SO2 per day, which while low-level compared to the output during fountaining episodes on the order of 200,000 tonnes, is still much greater than industrial standards. Both during and between episodes, 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/.
A deflationary cycle began coincident with the opening of vent 6 yesterday evening, bringing all activity at the vents to a halt by 8:30 PM. As usual, we summarize the monitoring signals, imagery, and reports available courtesy of the USGS Hawaiian Volcano Observatory as well as our broader community, annotating the presentation on-screen and discussing live viewer questions as we go.
