Report on Kilauea (United States) — 28 December-3 January 2012
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 28 December-3 January 2012
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2011. Report on Kilauea (United States). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 28 December-3 January 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 28 December-3 January, 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). Almost daily measurements indicated that the gas plume from the vent continued to deposit variable amounts of ash and fresh spatter nearby.
Incandescence was visible from small spatter cones on the E and S edges of the Pu'u 'O'o crater floor and along the 21 September 2011 fissure on the SE flank of the Pu'u 'O'o cone. Geologists on an overflight reported that pahoehoe lava flows were significantly broader (700-1,000 m) across the coastal plain and were entering the ocean along a 900 m wide area of the coast on 27 December. Lava flows continued to be active about 6.8 km SE of Pu'u 'O'o and entered the ocean W of Ka'ili'ili on 28 December. During 29 December-2 January a web camera showed no surface activity on the pali, weak sporadic flows near the coast, and weak plumes from the ocean entry. At night during 31 December-2 January incandescence was seen above the pali; on the night of 1 January ground based observers reported lava on the pali. Clouds prevented observations from a web camera on 3 January.
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.