Report on Kilauea (United States) — 23 May-29 May 2007
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 23 May-29 May 2007
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2007. Report on Kilauea (United States). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 23 May-29 May 2007. Smithsonian Institution and US Geological Survey.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
During 23-29 May, lava from Kilauea flowed SE across a growing lava delta into the ocean at the Poupou entry. By 24 May, lava no longer entered the ocean at the Kamokuna entry. Incandescence was visible from several vents in the Pu'u 'O'o crater and from breakouts above and at the base of the Pulama pali fault scarp. The earthquake swarm that began on 12 May continued S and E of Halema'uma'u, in the upper E rift zone, and at scattered locations in the S flank.
On 24 May, HVO recorded a M 4.7 earthquake at 0913, located beneath the upper E rift zone, near Puhimau crater, at a depth of 2 km. A M 4.1 aftershock occurred 20 minutes later and was located 1.5 km farther down-rift, beneath Koko'olau crater. A M 3.9 aftershock occurred at 1051 and was located another 2.5 km down-rift at a depth of 1 km. Since 1998, a few earthquakes with magnitudes greater than 4.0 have occurred at shallow depths beneath the upper E rift zone.
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.