Report on Kilauea (United States) — 15 August-21 August 2018
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 15 August-21 August 2018
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2018. Report on Kilauea (United States). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 15 August-21 August 2018. Smithsonian Institution and US Geological Survey.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
On 17 August HVO lowered the Alert Level for Kilauea to Watch (the Aviation Color Code remained at Orange), noting reduced activity over the previous several days. Specifically, no collapse events had occurred at the summit since 2 August, lava ceased flowing in the channel from the Fissure 8 cone on 6 August, seismicity and ground deformation at the summit were negligible, and the combined rate of sulfur dioxide emission from the summit and the LERZ were lower than any time since late 2007. The small lava pond in Fissure 8 had crusted over by 17 August, with no observed incandescence. Lava continued to ooze into the ocean at a few areas, causing minimal laze plumes. During an overflight on 20 August gas jets ejected spatter from a small incandescent area deep within the Fissure 8 cone.
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.