Report on Kilauea (United States) — 25 April-1 May 2001
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 25 April-1 May 2001
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2001. Report on Kilauea (United States). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 25 April-1 May 2001. Smithsonian Institution and US Geological Survey.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
Lava continued to flow down the Pulama pali and across the coastal flat. On 25 April a small stream of lava reached the sea for the first time since late January. The lava stopped trickling into the sea on 29 April. On that day an unstable block of the lava bench fell into the sea, producing a loud noise and generating an explosion that tossed rocks onto dry land. A M 4.4 earthquake on the afternoon of 25 April was followed by a few small aftershocks during the rest of the week. A swarm of long-period earthquakes that began on 18 April continued through at least 27 April. The tilt at the summit was neither flat nor consistently in one direction or the other. Tiltmeters along the east rift zone indicated that there was no significant deformation.
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.