Report on Kilauea (United States) — 16 September-22 September 2009
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 16 September-22 September 2009
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2009. Report on Kilauea (United States). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 16 September-22 September 2009. Smithsonian Institution and US Geological Survey.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
During 16-22 September, HVO reported that lava flowed SE from underneath Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex through a lava tube system, reaching the Waikupanaha ocean entry. Visual observations and thermal anomalies detected in satellite images revealed active surface lava flows.
The vent in Halema'uma'u crater continued to produce a diffuse white plume that drifted mainly SW. Small amounts of ash were retrieved from collection bins placed near the plume. The sulfur dioxide emission rate at the summit remained elevated; 1,300, 1,000, and 400 tonnes per day were measured on 16, 17, and 18 September, respectively. The 2003-2007 average rate was 140 tonnes per day. During 16 and 17 September, two hybrid earthquakes were followed by 20-40 minutes of sustained tremor. The plume turned briefly "dusty" after the first event and incandescent tephra was ejected onto the rim after the second event; both produced glassy spatter.
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.