Report on Kilauea (United States) — 1 April-7 April 2009
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 1 April-7 April 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, 1 April-7 April 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 1-7 April, 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. Surface flows on the coastal plain were seen or detected by satellite imagery. Occasional explosions occurred from the Waikupanaha ocean entry. On 2 April, geologists found that the surface lava flow feeding the Kupapa'u entry was 1 km (0.6 m) wide.
The vent in Halema'uma'u crater continued to produce a predominantly white plume that drifted mainly SW. Incandescence was intermittently seen from the vent, and sounds resembling rushing gas were sometimes heard in the vicinity of the crater. Variable amounts of tephra including some Pele's hair, Pele's tears, and rock dust were retrieved daily from collection bins placed near the plume. During 31 March and 1 April, geologists utilizing an infrared camera to look into the vent saw a lava pond that rose and fell approximately every 3 minutes. During 2-3 April, the lava pond was replaced by a large hot opening; ejected spatter built up a rim. The sulfur dioxide emission rate at the summit was elevated; measurements were 550, 800, and 700 tonnes per day on 1, 2, and 3 April, 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.