Report on Kilauea (United States) — 23 April-29 April 2008
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 23 April-29 April 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, 23 April-29 April 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 observations during helicopter overflights, visual observations from HVO and National Park Service (NPS) crews, and web camera views, HVO reported that during 23-29 April lava flowed SE through a lava tube system underneath Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex to the Waikupanaha ocean entry. Incandescence from breakouts along the lava-tube system was noted on 23 April.
During the reporting period, Kilauea summit earthquakes were located beneath the Halema'uma'u vent, beneath the S Kilauea caldera, NW of Pahala, along the S-flank faults, and along the SW rift zone. The eruption from the vent in Halema'uma'u Crater continued to produce white plumes with minor ash content that drifted mainly SW. During most nights incandescence was seen at the base of the plume. Seismic tremor was elevated.
Sulfur dioxide emission rates from the summit area have been elevated at 2-4 times background values since early January. On 28 April, the emission rate at the summit was 1,910 tonnes per day, compared to a background rate of 150-200 tonnes per day. According to news articles, Hawaii Volcanoes National Park closed during 24-25 April due to elevated levels of sulfur dioxide. About 2,000 people were evacuated from the Park.
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.