Report on Kilauea (United States) — 27 March-2 April 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 27 March-2 April 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, 27 March-2 April 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 27 March-2 April at Kilauea, activity continued at the rootless shields and surface lava flows were visible low on the Pulama pali scarp. On 27 March, just after 0300, a small earthquake beneath the caldera triggered more than 30 minutes of increased tremor and small earthquakes. Sharp deflation at Pu`u `O`o on 28 March accompanied a change in eruptive activity at the cone. Observations from a helicopter overflight revealed that new lava was visible just W of the main crater, as well as fountaining, and a circulating pond. By 31 March a lava flow was visible on the floor of Pu`u `O`o's crater and several vents were incandescent. On the 31st volcanic tremor was at low-to-moderate levels at Pu`u `O`o and weak tremor continued below Kilauea's caldera that was occasionally broken by small, long-period earthquakes. Tilt across the volcano was flat or only changed slightly.
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.