Report on Kilauea (United States) — 22 February-28 February 2012
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 22 February-28 February 2012
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2012. Report on Kilauea (United States). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 22 February-28 February 2012. 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 February, HVO reported that the lava lake circulated and periodically rose and fell in the deep pit within Kilauea's Halema'uma'u Crater. Web camera views and satellite images indicated that lava flows remained active within the abandoned Royal Gardens subdivision more than 7.5 km SE of Pu'u 'O'o. Lava flows also remained active high on the pali and across the December 2011 flows. Incandescence was visible on the NE and SE edges of the Pu'u 'O'o crater floor and on the upper part of the lava-tube system on Pu'u 'O'o's E flank during 23 and 26-28 February. On 22 February a small lava flow from the SE source was observed by the web camera. Two minor lava flows issued from the NE source on 26 February, and one lava flow issued from NE source on 27 February.
On 25 February HVO geologists aboard an overflight reported that the small cone on the NE source periodically ejected spatter, and the SE source fumed and produced a lava flow. They also noted that the flow advanced as two lobes; one lobe traveled along the E margin of the December 2011 flows and another advanced along the W margin of the December 2011 flows. During 27-28 February the web camera and satellite images indicated that both the E and W lobes continued moving down the pali.
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.