Report on Kilauea (United States) — 14 September-20 September 2011
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 14 September-20 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, 14 September-20 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 14-20 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. 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, lava in the E lava lake overflowed the E rim of Pu'u 'O'o crater on 13 September and advanced a few hundred meters. Lava erupted within the W lava lake and the next day overflowed the W edge of the crater through two broad gaps in Pu'u 'O'o cone, spreading up to several hundred meters downslope and mantling the W flank of Pu'u 'O'o. The flows had stopped by the evening of 15 September. During 15-16 September the level of the lava lakes had dropped 10-15 m. During 17-18 September the W lake was inactive and the E lake weakly bubbled and slowly circulated. Activity within the W lake increased abruptly on 19 September and, during 19-20 September, lava flowed across the W part of the crater floor. On 20 September lava refilled two perched lava ponds on the W edge of the crater, overflowed the southern-most pond, and produced a channelized lava flow that advanced 800 m down Pu'u 'O'o's W flank.
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.