The Lava Lake Returns to Kilauea

Kilauea summit lava lake at a depth of 515 ft (156 m) taken 8 a.m. Dec. 23. USGS photo by H. Dietterich

By Allison Kubo Hutchison

On December 20, 2020, at about 9:30 PM, Halema’uma’u Crater, the traditional home of the goddess Pele, hosted the first eruption of the Kilauea volcano since going silent in August 2018. Lava erupted from three vents in the crater’s sides and vaporized a small lake that had formed in the base of the crater. But a new lake began forming, a lake of lava.

Before the eruption began, earthquakes indicated that magma was moving beneath the surface of caldera. These signals would ramp up then down until an earthquake swarm occurred an hour before the eruption, and then the lake of water approximately 167 ft (51 m) deep began to boil off. At the beginning of the eruption, the emission of sulfur dioxide, a common volcanic gas that can cause air pollution, reached over 50,000 tonnes per day and then decreased for a week and remained roughly the same level of 5,000 tonnes day, according to the US Geological Survey.

The three vents in the caldera’s side fed a growing lava lake, which as of January 30, 2021, over a month of continuous eruption, reached a depth of 692 ft (211 m). Then vents had fountaining lava driven by gas within the lava that exsolves as it rises through the crust. The lava lake is now deeper than the Seattle Space Needle is tall (602 ft) and covers an area of over 69 acres, an area larger than the US Capitol building (57 acres) or Grand Central Station (50 acres). There is a floating “island” of erupted material within the lava lake, which is thought to have been generated by lava-water interactions when the eruption first began and flowed into the water lake at the bottom of the crater. When water and lava interact, the lava’s high heat vaporizes the water, and the addition and sudden expansion of a gas can cause explosive reactions. At the onset of the eruption, a steam plume rose from the crater but was quickly boiled off.

This isn’t the first time the crater has been home to a lava lake, as there was a lava lake present at the summit from 2008 to 2018 when it drained in the Puna eruption. With the Kilauea lava lake’s return, there are currently eight active lava lakes throughout the world. Lava lakes provide a window into magma dynamics and the magmatic conduit, which pipes magma from the reservoir to the surface. Particularly, the gases that come off the lava lake can help understand the subsurface conditions.

Refer to HVO for updates.

This map of Halema‘uma‘u at the summit of Kīlauea shows 20 m (66 ft) contour lines (dark gray) that mark locations of equal elevation above sea level (asl). The map shows that the lava lake (approximate area marked in red) has filled 184 m (603 ft) of Halema‘uma‘u since the eruption began at approximately 9:30 p.m. HST on December 20, 2020. USGS map.

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