Report on Kilauea (United States) — 19 February-25 February 2003
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 19 February-25 February 2003
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2003. Report on Kilauea (United States). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 19 February-25 February 2003. Smithsonian Institution and US Geological Survey.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
During 20-24 February at Kilauea, a small amount of lava entered the sea at the West Highcastle entry, and W of there lava flowed into the sea at the Kohala entry (an event that began on 15 February). Fresh lava oozed out of the cooling Kohala lava flow, both within the body of the flow and along its E margin. During the report period, lava continued to cross the Chain of Craters Road. Generally, seismicity remained at normal levels, with the long-lasting swarm of long-period earthquakes and tremor at Kilauea's summit, which began last June, continuing at low-to-moderate levels. Moderate tremor was recorded by the nearest seismometer to Pu`u `O`o. During 17-21 February, several small periods of inflation and deflation, which were consistent with each other in magnitude and patterns, were recorded at Uwekahuna and Pu`u `O`o tiltmeters.
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.