Report on Kilauea (United States) — 16 July-22 July 2008
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 16 July-22 July 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, 16 July-22 July 2008. Smithsonian Institution and US Geological Survey.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
Based on visual observations from HVO crews, video footage, pilot reports, and web camera views, HVO reported that during 16-22 July, lava flowed SE through a lava tube system from underneath Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex. The lava flowed into the ocean at the Waikupanaha ocean entry resulting in occasional explosions and a vigorous steam plume from contact with the water. Lightning was sometimes seen in the steam plume. Incandescence was observed from the TEB vent, rootless shields, breakouts along the W margin of the TEB lava tube, and from vents and sporadic spatter in Pu'u 'O'o crater. The sulfur dioxide emission rate at Pu'u 'O'o was very high at 6,300 tonnes per day on 17 July; the average background rate is about 2,000 tonnes per day.
During the reporting period, Kilauea earthquakes were located beneath the summit area and beneath Halema'uma'u crater, along S-flank faults, and along the E and SW rift zones. Beneath Halema'uma'u crater, another 20-40 small earthquakes per day also occurred but were too small to be located. The vent in the crater continued to produce a white plume with minor ash content that drifted mainly SW. Night-time incandescence was seen at the base of the plume. Rock clattering, booming noises, and "rushing sounds" were heard in the vicinity of Halema'uma'u crater. The sulfur dioxide emission rate was high and between 700 and 800 tonnes per day, during 16-18 July. The pre-2008 background rate was 150-200 tonnes per day. On 19 July, incandescent material was ejected from the vent.
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.