Report on Kilauea (United States) — 3 December-9 December 2008
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 3 December-9 December 2008
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2008. Report on Kilauea (United States). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 3 December-9 December 2008. 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 3-9 December lava flowed SE through a tube system from underneath Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex, reaching the Waikupanaha ocean entry. Incandescence was occasionally seen at the TEB vent, and surface flows were noted on and at the base of the pali. On 6 December, a few explosions originated from the ocean entry. Observers reported that a small bench collapse that occurred sometime between 6 and 7 December sent boulders up to 0.5 m in diameter inland about 50-75 m.
Earthquakes were variously located beneath and to the S of the caldera, along the SW rift zone, and along the S-flank fault. The vent in Halema'uma'u crater continued to produce a predominantly white plume that drifted mainly SW and deposited small amounts of tephra. Night-time incandescence was rarely seen at the base of the plume, and sounds resembling rockfalls were heard in the vicinity of the crater. During 2-4 December, the plume drifted NW and high concentrations of sulfur dioxide were measured at various locations. On 4 December, hybrid earthquakes were followed by several minutes of dense brown emissions. A vent rim collapse was seen on 5 December after rockfall and booming sounds were heard, and brown ash was emitted. The sulfur dioxide emission rate at the summit was 1,000 and 500 tonnes per day on 4 and 5 December, 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.