Report on Kilauea (United States) — 21 December-27 December 2011
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 21 December-27 December 2011
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, 21 December-27 December 2011. Smithsonian Institution and US Geological Survey.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
During 21-27 December, 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. On 22 December the SW vent wall collapsed into the lake, ejected lava onto the inner ledge, and caused an increased amount of ash in the plume.
Incandescence was visible from small spatter cones on the E and S edges of the Pu'u 'O'o crater floor. Pahoehoe lava flows, that were 300-400 m wide and fed by lava tubes from the fissure, continued to be active about 6.8 km SE of Pu'u 'O'o and entered the ocean W of Ka'ili'ili. During 25-26 December the tube appeared to be more robust and less surface flow activity was reported. Small plumes were observed from the ocean entry during 22-24 December and infrequent weak plumes were observed during 25-26 December. On 27 December a breakout of lava flows were visible on the pali (a fault scarp).
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.