Report on Kilauea (United States) — 17 July-23 July 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 17 July-23 July 2002
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2002. Report on Kilauea (United States). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 17 July-23 July 2002. Smithsonian Institution and US Geological Survey.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
During 16-22 July, surface lava flows were visible traveling on the coastal flat, down the Pulama pali scarp, and down Paliuli, the steep slope and cliff below Pulama pali and just above the coastal flat. On 20 July at 1900 part of the westernmost lava flow reached Chain of Craters road, and by 0445 the next day it was entering the sea in two areas. The active flow front moved relatively quickly for lava at Kilauea on nearly flat ground; the lava flow moved 610 m in 18 hours (35 m/h). Generally, seismicity was at normal levels, except for the continued swarm of long-period earthquakes and tremor that has been ongoing since early June. The swarm increased slightly in the last several days of the report period. Slow deflation occurred at Pu`u` O`o.
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.