Report on Kilauea (United States) — 18 February-24 February 2009
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 18 February-24 February 2009
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2009. Report on Kilauea (United States). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 18 February-24 February 2009. 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 during 18-24 February lava flowed SE from underneath Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex through a lava tube system, reaching the Waikupanaha ocean entry and occasionally producing explosions. On 17 February, four large explosions that accompanied a collapse of the Waikupanaha bench ejected rocks and spatter 275 m inland. Lava also entered the ocean at Waha'ula during 18-20 February, and at a second point further E, named Poupou, starting on 18 February. Incandescence originated from the Prince lobe on 20 February. Thermal anomalies noted on the coastal plain suggested surface flows.
The vent in Halema'uma'u crater continued to produce a predominantly white plume that drifted mainly SW; incandescence was intermittently seen from the vent. Small amounts of ejected tephra, including Pele's hair and some spatter, were routinely collected. Geologists utilizing an infrared imager during an overflight on 20 February saw a small, hot degassing vent deep below the vent rim. The sulfur dioxide emission rate at the summit was 1,400, 1,500, 1,300, and 900 tonnes per day on 17, 18, 19, and 20 February, respectively; the 2003-2007 average rate was 140 tonnes per day.
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.