Report on Kilauea (United States) — 23 September-29 September 2009
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
23 September-29 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, 23 September-29 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 23-27 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. Lava was not seen entering the ocean on 28 and 29 September. Visual observations and thermal anomalies detected in satellite images revealed active surface lava flows on most days. On 23 September, weak incandescence was detected from inside Pu'u 'O'o crater and from a gas vent in the E crater wall. Explosive activity at the ocean entry on 26 September was possibly caused by a small bench collapse.
The vent in Halema'uma'u crater continued to produce a diffuse white plume that drifted SW and W. Small amounts of ash were retrieved from collection bins placed near the plume. Weak incandescence from the vent, about 200 m below the Halema'uma'u crater floor, was visible at night. Rushing gas and rockfall sounds were occasionally heard in the vicinity of the vent. Preliminary measurements indicated that the sulfur dioxide emission rate at the summit remained elevated; 400, 700, and 665 tonnes per day were measured on 23, 24, and 28 September, respectively. The 2003-2007 average rate was 140 tonnes per day. On 26 September, a series of rockfalls accompanied an apparent collapse of the vent floor, causing the lava level to drop and the plume to turn "dusty brown" for several minutes. On 28 September, a spattering lava pond was seen inside the vent.
Geological Summary. 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.