Report on Kilauea (United States) — 18 July-24 July 2018
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 18 July-24 July 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, 18 July-24 July 2018. 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 at Kilauea’s Lower East Rift Zone (LERZ) and within Halema`uma`u Crater continued during 18-24 July. Lava fountaining and spatter was concentrated at Fissure 8, feeding lava flows that spread through Leilani Estates and Lanipuna Gardens subdivisions, and built out the coastline at multiple ocean entries.
Inward slumping of the crater rim and walls of Halema`uma`u continued, adjusting from the withdrawal of magma and subsidence of the summit area. Explosions from collapse events occurred almost daily, often followed by a surge in activity at Fissure 8. Sulfur dioxide emissions from the summit were very low.
Fountaining at Fissure 8 continued, producing Pele's hair and other volcanic glass that fell within Leilani Estates. The fountains continued to feed the lava flow that traveled NE, and then SSE, W of Kapoho Crater. Channel overflows on 18 July destroyed structures in the Leilani Subdivision. The channelized ‘a’a flow was incandescent along its entire length as it flowed towards the ocean. It generated plumes of laze (a corrosive steam plume mixed with hydrochloric acid and fine volcanic glass particles) at several points along a broad 6-km-wide flow front, though the main entry area was at Ahalanui, a few hundred meters E of the flow edge which was 175 m NE of Isaac Hale Park (by 24 July). HVO noted that the lava delta was unstable as it has been built out as far as 800 m from the original coastline on unconsolidated lava fragments and sand.
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.