Report on Kilauea (United States) — 15 October-21 October 2008
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 15 October-21 October 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, 15 October-21 October 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 15-21 October lava flowed SE through a tube system from underneath Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex, reaching the Waikupanaha ocean entry. Multiple surface lava flows on the pali were noted; on 16 October a channelized 'a'a flow was active in the Royal Gardens subdivision and a pahoehoe flow was seen on the W side of the active flow field. Lava destroyed one of two remaining intermittently occupied structures in the subdivision. The sulfur dioxide emission rate at Pu'u 'O'o was 1,000 tonnes per day on 17 October, half of the background rate of the 2005-2007 average. Explosions at the ocean entry were reported on 19 October.
During the reporting period, Kilauea earthquakes were variously located beneath and to the S of the caldera, and along the S-flank faults. Beneath Halema'uma'u crater earthquakes ranged from 40 per day to more than 100 (background is about 40), but were too small to be located more precisely. The vent in Halema'uma'u crater continued to produce a predominantly white plume, which was occasionally tinged brown in association with small local earthquakes or vent rim collapses, that drifted mainly SW. Night-time incandescence was intermittently seen at the base of the plume. Two vent explosions occurred on 14 October. The first was initiated by the collapse of a thin piece of the vent rim. The second explosion ejected molten spatter that fell within 100 m of the vent and produced an eruption plume that rose 2 km above the caldera rim. The sulfur dioxide emission rate was 600 and 900 tonnes per day on 16 and 17 October, respectively. The 2003-2007 rate average 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.