Report on Kilauea (United States) — 21 April-27 April 2021
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 21 April-27 April 2021
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2021. Report on Kilauea (United States) (Sennert, S, ed.). Weekly Volcanic Activity Report, 21 April-27 April 2021. Smithsonian Institution and US Geological Survey.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
HVO reported that the W vent on the inner NW wall of Kilauea's Halema`uma`u Crater continued to supply the lava lake during 21-27 April. Lava flowed at a low rate from the main vent into the lake through crusted-over channels and submerged inlets. The depth of the lake was about 226-227 m and lava continued to circulate in the W part, though the active area continued to shrink; the E half of the lake remained solidified. Lava sometimes overflowed the margins of the lake. The sulfur dioxide emission rate was 350, 550, 300, and 350 tons/day on 21, 22, 23, and 24 April, respectively. The rates were the lowest measured during the eruption, though elevated above the levels recorded in the months before the start of the eruption (20 December 2020). The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.
Geological Summary. Kilauea overlaps the E flank of the massive Mauna Loa shield volcano in the island of Hawaii. Eruptions are prominent in Polynesian legends; written documentation since 1820 records frequent summit and flank lava flow eruptions interspersed with periods of long-term lava lake activity at Halemaumau crater in the summit caldera until 1924. The 3 x 5 km caldera was formed in several stages about 1,500 years ago and during the 18th century; eruptions have also originated from the lengthy East and Southwest rift zones, which extend to the ocean in both directions. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1,100 years old; 70% of the surface is younger than 600 years. The long-term eruption from the East rift zone between 1983 and 2018 produced lava flows covering more than 100 km2, destroyed hundreds of houses, and added new coastline.