Report on Kilauea (United States) — 6 May-12 May 2009
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 6 May-12 May 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, 6 May-12 May 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 6-12 May, 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 and Kupapa'u ocean entries. On 6 May, a bench collapse from Kupapa'u was detected by seismic signals. Tour pilots reported an active surface lava flow above the pali that was less than half a kilometer long. A thermal anomaly corresponding to the flow was detected on satellite imagery. Geologists on an overflight on 7 May mapped a stalled 'a'a flow that broke out from the TEB lava tube and was being covered by pahoehoe from the breakout point. They also saw that the Waikupanaha delta had built out to the furthest point in its over 13-month history and that bus-sized chunks of delta were scattered on the beach fronting the Kupapa'u entry, as a result of the 6 May collapse. Some explosions occurred at the Waikupanaha ocean entry on 10 May.
The vent in Halema'uma'u crater continued to produce a white plume that that drifted W and SW. A molten lava pool near the base of the cavity, deep below the floor of the crater, produced the brightest incandescence from the summit vent since early December 2008. Sounds resembling rushing gas and falling rocks were sometimes heard in the vicinity of the crater. Fresh spatter was retrieved from collection bins placed near the plume during 6-7 May. The sulfur dioxide emission rate at the summit was elevated; measurements were 1,100 and 700 tonnes per day on 8 and 10 May, respectively. The 2003-2007 average rate was 140 tonnes per day.
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.