Hawaiian Volcano Update: Kīlauea's Short Eruption Followed by Recharge

Following its latest, 12-day eruption, Kīlauea shows little surface change, but monitoring instruments suggest the volcano has quickly resumed inflating as it recharges with magma underground. In the 3.5 weeks since the eruption ended, the ground surface appears to be steadily tilting outwards and rising around the eruption site, even as the calderaʻs horizontal expansion has slowed more recently. Unlike the build-up to the June 2023 activity, earthquake rates are moderately low, but this might be partly explained by the gas-rich nature of the most recent eruptive episode. The USGS Hawaiian Volcano Observatoryʻs summary map reports 9.1 million cubic meters (MCM) of lava were erupted, even though the eruption area was initially swollen with 14.6 MCM of extra volume as the eruption ramped up. They attribute this change to the lava lake being “somewhat inflated during its early hours thanks to a massive amount of volcanic gas trapped within the erupted material. But over the coming hours and days, the gas escaped and the lake deflated somewhat. The dropping surface left a ʻbathtub ringʻ of crust around the edges, marking the initial high-lava level in many photos shared by HVO scientists.” The extra 60%, or 5.5 MCM, was vented as gas! The gas-rich, buoyant lava may thus have put extra pressure on the system before it erupted. Following this theme, the reported SO2 output of over 75,000 tonnes on the eruptionʻs first day (June 7) far exceeds the 12,500 tonnes reported at the start of the January 6, 2023 eruption. The comparison is certainly influenced by the fewer hours from onset to sampling in June, with HVO scientists completing their measurements only 4 hours in due to the eruptionʻs timing at the start of the day, but the difference is still striking. Presently, SO2 emissions have returned to background levels, around 170 tonnes per day last week, but still present the largest threat to nearby populations and sensitive individuals. Changes in the lava lakeʻs elevation following the halt of surface lava effusion on June 19 present another curiosity, with the single measurement site in the western basin showing rough increases of 2 meters from June 19-22 and 1.5 meters from June 25-28. If these gains are representative of the larger crater floor, then the deeper conduit into the lava lake may have remained intact and able to feed magma beneath the crust during those times. On the other hand, the asymmetrical progression of the eruptive area to the southwest surely tilted the craterʻs crust, which could since have re-leveled itself atop the fluid magma and gas still trapped below. The bottom line is that after the short eruption, there are still plenty of volcanic adjustments ongoing and magma is again building pressure underground. The continued evolution of the magmatic plumbing through each new eruption still presents a unique combination of signals, leading to new questions and mysteries, and hints at a changing dynamic. The two most recent eruptions have been of relatively short duration after short periods of repose, with short run-up times to each eruption. Given the pattern, the next event could also ramp up, erupt, and end quickly, but how soon? How easily could magma push through its recen surface conduits? As usual only time will tell, as we track these smaller changes looking for clues. Maunaloa remains quiet as magma continues the normal process of refilling its summit reservoir, with no further changes to report. Our live presentation reviews the recent changes using monitoring data, imagery and reports courtesy of the USGS Hawaiian Volcano Observatory. We annotate the presentation on-screen, and discuss live viewer questions.