Report on Kilauea (United States) — 1 February-7 February 2012
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 1 February-7 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, 1 February-7 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 1-7 February, HVO reported that the lava lake circulated and periodically rose and fell in the deep pit within Kilauea's Halema'uma'u Crater, remaining below the inner ledge (75 m below the crater floor). On 1 February lava ejections on the S edge rebuilt a low spatter cone. On 3 February two large rockfalls into the lake originated from the Halema'uma'u Crater floor. The first collapse from the N rim induced secondary collapses of the inner ledge and ejected spatter onto nearby portions of the Halema'uma'u Crater floor. The second collapse deposited large amounts of debris into the NE side of the lava lake.
At Pu'u 'O'o short lava flows issued from the SE vent during 1-2 February. Incandescence was visible on the NE and SE edges of the Pu'u 'O'o crater floor during 3-7 February and from a small cone on the NE edge during 5-7 February. The web camera showed incandescence reflected in the clouds above the pali on 2 and 4 February. During 1-7 February, thermal anomalies were seen in satellite imagery 4-5 km SE of Pu'u 'O'o cone.
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.