Report on Kilauea (United States) — 30 December-5 January 2021
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 30 December-5 January 2021
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2020. Report on Kilauea (United States). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 30 December-5 January 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 lava effusion from a vent on the inner NW wall of Kilauea’s Halema`uma`u Crater continued to feed a growing lava lake during 30 December-5 January. A cone had formed over the remaining active vent, which was one of three that had opened at the beginning of the eruption. Lava sometimes spattered from vents at the top of a cone and flowed down into the lake through a crusted-over channel; during 2-5 January a dome fountain was visible near the lake’s margin, formed by upwelling of lava as in entered the lake at a partially submerged inlet.
The lake deepened from 181 m on 30 December to 191 m by 4 January, and the lake volume was an estimated 26 million cubic meters by 4 January. An island of cooler, solidified lava continued to float around on the lava lake’s surface, and by 4 January the island’s surface was 1-2 m above the surface of the lava lake. Over the week the island was joined by less than a dozen other small islands of cooled and solidified material that also moved around, though they mostly remained in the eastern part of the lake. The lava lake was also becoming perched as overflows of lava onto the narrow edge formed around the lake’s margins continued to build a levee; by 3 January the lake was perched about 1 m above the margin. Sulfur dioxide emissions fluctuated between 3,000 and 6,500 tonnes/day. Seismicity remained elevated but stable.
Geologic Background. Kilauea, which overlaps the E flank of the massive Mauna Loa shield volcano, has been Hawaii's most active volcano during historical time. Eruptions are prominent in Polynesian legends; written documentation extending back to only 1820 records frequent summit and flank lava flow eruptions that were interspersed with periods of long-term lava lake activity that lasted until 1924 at Halemaumau crater, within the summit caldera. The 3 x 5 km caldera was formed in several stages about 1500 years ago and during the 18th century; eruptions have also originated from the lengthy East and SW rift zones, which extend to the sea on both sides of the volcano. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone that began in 1983 has produced lava flows covering more than 100 km2, destroying nearly 200 houses and adding new coastline to the island.