Report on Kilauea (United States) — 7 September-13 September 2011
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 7 September-13 September 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, 7 September-13 September 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 31 August-6 September, HVO reported that the level of the lava-lake surface in the deep pit within Kilauea's Halema'uma'u crater periodically fluctuated and circulated. Almost daily measurements indicated that the gas plume from the vent continued to deposit variable amounts of ash and occasionally fresh spatter nearby. At Pu'u 'O'o' crater, lava from E, W, and S-central sources on the crater floor fed an eastern and a western perched lava lake during 7-8 September. Lava also covered much of the crater floor, rising to within 5 m of a low point on the E crater rim. During 9-10 September a large amount of lava from a new source of effusion at the NE edge of the crater covered most of the crater floor. On 10 September a pilot confirmed that lava overtopped the E rim and fed a short lava flow. Not long after that the effusion rate decreased and lava fed only the two perched lava lakes. During 11-13 September the lava lakes mostly circulated and, by 12 September, had overflowed onto 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.