Report on Kilauea (United States) — 22 April-28 April 2009
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 22 April-28 April 2009
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2009. Report on Kilauea (United States). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 22 April-28 April 2009. Smithsonian Institution and US Geological Survey.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
During 22-28 April, HVO reported that lava flowed SE from underneath Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex through a lava tube system, reaching the Waikupanaha and Kupapa'u ocean entries. Occasional explosions occurred from the Waikupanaha ocean entry, and on 22 April small littoral explosions continued to build up a steep-sided cone at the Kupapa'u entry. Surface flows were present on the coastal plain. The vent in Halema'uma'u crater continued to produce a white plume occasionally tinged brown that drifted SW, N, and NE. Poor air quality in nearby communities was sometimes caused by the plume. Incandescence was intermittently seen from the vent, and sounds resembling rushing gas or rockfalls were sometimes heard in the vicinity of the crater. Various amounts of tephra, including Pele's hair, spatter, and ash, were frequently retrieved from collection bins placed near the plume.
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.