Report on Kilauea (United States) — 23 December-29 December 2020
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 23 December-29 December 2020
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, 23 December-29 December 2020. 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 eruption from N and W fissure vents on the inner walls of Kilauea’s Halema`uma`u Crater continued to feed a growing lava lake during 23-29 December. Lava erupted from the N and W vents during 23-26 December with lava fountains that were sometimes 10 m high. The lake level rose above the N vent by 0300 on 26 December; later that day, volcanologists noted that the lake was slowly draining at that location. The W vent continued to feed the lake during 27-29 December. An island of cooler, solidified lava (250 m by 135 m in dimension on 28 December) slowly floated around on the lava lake’s surface. The island’s surface was about 6 m above the surface of the lava lake and was covered in tephra, possibly remnants of explosive activity generated when lava first reached the water lake.
The depth of the lava lake increased from 155 m to 169 m during 23-24 December. It continued to rise and was 176 m deep by 1400 on 25 December, though a new, narrow, black rim along the N edge suggested that the lake had briefly been 1-2 m deeper, and then drained back. The lake remained 176-177 m deep through 28 December, but by 29 December had deepened to 180 m. The lake volume was an estimated 22 million cubic meters, and was 770 by 490 m in dimension by 29 December.
Sulfur dioxide emissions decreased over the week, from around 30,000-40,000 tonnes/day on 23 December, to 20,000 tonnes/day on 25 December, 5,000-5,500 tonnes/day during 26-27, and finally dropping to 3,000 tonnes/day during 28-29 December. The emission plume carried Pele’s Hair and Pele’s Tears SW, depositing the tephra in areas downwind, including on HVO monitoring equipment and solar panels.
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.