Report on Kilauea (United States) — 28 September-4 October 2011
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 28 September-4 October 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, 28 September-4 October 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 28 September-4 October, HVO reported that the lava lake circulated and periodically rose and fell in the deep pit within Kilauea's Halema'uma'u crater. Almost daily measurements indicated that the gas plume from the vent continued to deposit variable amounts of ash and occasionally fresh spatter nearby.
At the E rift zone, the fissure that formed on 21 September on the upper E flank of Pu'u 'O'o continued to feed lava flows on 28 September that traveled along the edges of a low lava ridge. Most of the active lava spread out at higher elevations S and W of Pu'u Halulu (1.3 km NE of Pu'u 'O'o). Lava activity resumed from two sources on the E edge of the Pu'u 'O'o Crater floor and continued to spread W within the crater. During an overflight on 29 September, geologists observed that the fissure fed scattered active lava flows within 1.8 km on the SE flank of the cone. During 2-3 October lava from the E-crater floor source covered the crater floor. On 4 October active lava was confined to a small lake on the E side of the crater floor.
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.