Graph showing lava depth (in meters) that has filled Halema‘uma‘u crater, at Kīlauea volcano's summit, after the 2018 collapse, since December 2020. On January 8, 2021, a novel laser rangefinder was stationed at Kīlauea volcano's summit. The fixed instrument continuously measures the distance to a location on the western lava lake surface, and telemeters data to HVO in real time. The raw data has been edited for this graph, with a running mean average filter of 3600 seconds. Variations in plotted depth can occur due to laser rangefinder returns on gas rather than the lava surface.

For reference, the base of Halema‘uma‘u after the 2018 collapse event is “zero” on this plot (equal to an elevation of 518 meters/1699 ft above sea level). Post-eruption analyses indicate that the December 2020–May 2021 lava lake filled the base of Halema‘uma‘u to a depth of 223 meters/732 ft (equal to an elevation of approximately 741 meters/2431 ft above sea level). The ongoing eruption is adding to that lava depth. Lava will overflow Halema‘uma‘u, onto the lowest down-dropped block, at a depth of 267 meters/876 ft (equal to an elevation of 790 meters/2592 ft above sea level).

Sulfur dioxide (SO₂) emission rates measured using an upward-looking ultraviolet spectrometer. These data are collected by traversing the gas plume in a vehicle or helicopter, downwind of Halema‘uma‘u, generally within and/or southwest of Kīlauea caldera. Results from multiple traverses during a day are averaged to yield the emission rates shown here. Successful measurements depend on wind, weather, and staff availability. Values are preliminary and are subject to revision.

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 filled 229 m (752 ft) of the crater, to an elevation of 747 m (2450 ft) asl, from the beginning of the eruption on December 20, 2020, through May 13, 2021. Over this period, a total of 41 million cubic meters (11 billion gallons) of lava was erupted into the crater, filling approximately 5 percent of the volume that collapsed within the caldera during the 2018 eruption. The graphic at the bottom shows topographic profiles from west to east across the caldera before 2018, shortly after 2018, and as of May 13, 2021, along with the 2019-2020 Halema‘uma‘u water lake. The last activity on the lava lake surface was observed on May 23 and on May 26, 2021, the USGS Hawaiian Volcano Observatory lowered the Volcano Alert Level for ground-based hazards from WATCH to ADVISORY and the Aviation Color Code from ORANGE to YELLOW. USGS map.