Report on Kilauea (United States) — 17 August-23 August 2011
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 17 August-23 August 2011
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2011. Report on Kilauea (United States). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 17 August-23 August 2011. Smithsonian Institution and US Geological Survey.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
During 17-23 August, HVO reported that lava continued to trickle onto the collapsed floor of Kilauea's Pu'u 'O'o' crater and some spattering occurred from various areas on the floor. The only activity on the W flank was observed during 17-20 August; a small lava flow from the base of the N pond rim near the Kamoamoa fissures and a larger flow from the N flow branch were both active. During 20-21 August a small amount of lava emitted from a vent on the S crater floor flowed a short distance. Later, lava started issued in larger quantities from another source on the S part of the floor that quickly filled in a low trench. Lava continued to flow onto the crater floor during the next two days.
During 17-18 August lava flowed onto the floor of the vent inset within the E wall of Halema'uma'u Crater. By the next day a persistent spattering source at the W edge of the cavity pushed the lava surface sluggishly from W to E. During 19-21 August drain-and-fill cycles were observed; the highest level of the lava surface was below the inner ledge 75 m below Halema'uma'u Crater floor.
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.