Report on Kilauea (United States) — 20 August-26 August 2008
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
20 August-26 August 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, 20 August-26 August 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 20-26 August, lava flowed SE through a lava tube system from underneath Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex to the Waikupanaha ocean entry. On 20 August, geologists observed bursting lava bubbles from an area E of Waikupanaha that threw molten fragments 10-20 m into the air. The sulfur dioxide emission rate at Pu'u 'O'o was 3,200 and 1,800 tonnes per day on 20 and 22 August, respectively; the average background rate is about 2,000 tonnes per day.
Kilauea earthquakes were centered in various locations along the Koa'e fault system, S and W of the caldera, beneath the summit, along the S-flank faults, and along the E and SW rift zones. Beneath Halema'uma'u crater, more than 40 small earthquakes per day (background 40) also occurred but were too small to be located more precisely. About 100 earthquakes were detected on 26 August. The vent in Halema'uma'u crater continued to produce a predominantly white plume with minor ash content that drifted mainly SW. The plume was occasionally tinged brown. Weak night-time incandescence was intermittently seen at the base of the plume, and rock impacts and muted rushing sounds were heard in the vicinity of the crater. On 21 August, an earthquake was accompanied by a 400-m-high jet of mostly gas that rose vertically, then drifted SW. The jet also contained some rock dust and bits of volcanic glass. Several small ash ejections occurred on 25 August. The sulfur dioxide emission rate was 600-1,000 tonnes per day during 20-25 August. The pre-2008 background rate was 150-200 tonnes per day.
Geological Summary. 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.