Report on Kilauea (United States) — 14 January-20 January 2004
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
14 January-20 January 2004
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2004. Report on Kilauea (United States). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 14 January-20 January 2004. Smithsonian Institution and US Geological Survey.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
On 18 January during 0550 to 0830 a large period of deflation occurred at Kilauea's Pu`u `O`o cone, amounting in 18.1 microradians of net deflation. During this period a fissure opened at the SE base of Pu`u `O`o, trending approximately radial to the cone. Lava was emitted from the fissure and from three to four vents nearby. The initial flow reached about 1.5 km S of the cone. The S side of Pu`u `O`o was cut by many new fractures. The longest fracture constituted the N boundary of a shallow graben (a linear trough bounded by faults) that was ~75 m long and up to 1 m deep. Surface lava flows were emitted from the E end of the graben, at the base of Pu`u `O`o. The area S of Pu`u `O`o cone appeared to be quite unstable, so HVO scientists warned that no one should venture into the area. Seismicity at Kilauea's summit during 15-20 January was at low levels, while tremor at Pu`u `O`o was continuous and at moderate levels. The tremor picked up during the formation of the graben on 18 January. As of 20 January tilt continued to steadily decline following the 18 January deflation event.
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.