Kīlauea Eruption Update, Week 20: May 11, 2021

The transformation of Kīlauea’s lava lake continues after a third consecutive week of crusting, which has reduced and reshaped its open lava surface. Gas emissions dropped to 150 tonnes/day on May 10 according to USGS-HVO, a new low for the eruption that has been ongoing for nearly 5-months, and well within the range of historic non-eruptive background measurements. This suggests that much less lava is erupting, and it could soon stop. Perhaps due to the effect of lessened gas, the lava lake surface has been cooling and solidifying more quickly on its surface, and rafts of the crust continue to be carried by the liquid beneath. These have continued to stack around the lake margin, as well as the narrow points between cooling islets to form an inner perched pond near the lava inlet, essentially dividing the remaining open lava lake into upper and lower perched ponds. Now, lava rises below the West Vent and enters the inner, highest pond through a submerged inlet, before it cascades through gaps on the far side into the lower perched pond, and ultimately disappears beneath the hardening surface towards the edge of the eruption’s big island. While previously the lava was seen to re-emerge along the crater walls through “ooze-up flows”, no such occurrences have been observed in nearly a month. Deflation-inflation ground tilt cycles still continue frequently, though have been smaller in magnitude over the past week. Since these variations can visibly affect the amount of lava entering the crater, the relative stability combined with the damming effect has allowed lava levels to continue to rise within the smaller inner pond, reaching a new depth of 751 ft (229 m). However, GPS-measured caldera spreading continues, suggesting further complexity of the magmatic system as it develops following the 2018 caldera collapse. Latest on Kīlauea, Eruption Day 142, Week 20: -Lava lake surface crusting still ongoing; rafted crusts form a smaller, inner perched lava pond which cascades into the original, lower lava pond. -Gas emissions remain low, within background range, despite smaller DI cycles -GPS shows continued caldera spreading, with extension rates returning to the recent average following last week’s larger DI cycles. Seismic activity also has kept within background levels, this past week focused mainly around the summit and south flank. We review the details of the ongoing changes to the open lake surface using original time-lapse productions, live monitoring data and published photos and reports available courtesy of the USGS Hawaiian Volcano Observatory. As usual, we discuss live viewer questions! https://www.youtube.com/watch?v=SlayMP-Mh1c