Hawaiian Volcano Update: Kīlauea Magma Pressures Weak Areas Beneath Summit - October 15, 2026
Activity at the main vent complex at Kīlauea’s summit built from flames and spatter at the end of last week to a small, tube-fed flow early on Sunday, and then to periods of low fountaining with overflows from the north vent on Monday and Wednesday, with the south vent also overflowing on Wednesday. According to the USGS Hawaiian Volcano Observatory, “it is possible that another fountaining episode from the north-south vent complex could occur; however, intrusive activity underneath Kaluapele is also possible, or magma could exploit existing weak crack systems in the summit region to erupt passively (with little to no seismicity or deformation).”
Shallow summit earthquakes mostly beneath the south caldera have been elevated over the past week, with USGS reported counts of 7 for Thursday, 24 for Friday, 26 for Saturday, 23 for Sunday (13 coincident with a notable tilt drop), then 20, 22, and 20 for Monday, Tuesday, and Wednesday. Under the north caldera, updated InSAR data “show the intrusion has been slightly contracting since the evening of October 2. Minor intrusion-related motion was observed along many faults and cracks formed during the 2018 caldera collapse. There are no signs of significant deformation outside the caldera, including the south caldera region” although as noted earlier, little to no deformation might be expected.
The overall interpretation remains that “the rising elevation of the established north-south-west vents over the course of this eruption has increased the pressure necessary to push magma out of the vents and trigger a major fountain episode.” Further, “the occurrence of these two small-volume intrusions below Kīlauea’s summit region within the past month suggests the pressure required to erupt dense degassed magma from the established vents is also high enough to allow magma to exploit weakenesses below the surface along the pre-existing, 2018 crack systems.” Potential outcomes listed by the USGS include a return to fountaining, formation of new summit vents, intrusion into the upper rift zones, continued summit intrusions, or an end to the eruption.
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. Trade winds are expected to dominate this week, potentially carrying emissions substantial distances across the south side of the island, wrapping around to the Kona coast. Both during and between episodes and new outbreaks, 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/.
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.
