Report on Kilauea (United States) — 4 April-10 April 2001
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 4 April-10 April 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, 4 April-10 April 2001. Smithsonian Institution and US Geological Survey.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
Moderate eruptive activity was visible during most of the week, but during 7-9 April Kilauea also went through phases of deflation, inflation, and increased seismicity. On 7 April, lava flowed down the Pulama Pali in two surface streams. At 0300 on 7 April summit tiltmeters began to show deflation, and starting at ~0620 volcanic tremor and long-period earthquakes increased. The phase ended in the early afternoon with a total of 3 microradians of deflation. By 8 April there was no glow from surface flows on or above Pulama Pali, which indicated that an apparent pause in the eruption occurred the previous day. At ~0200 on 8 April the summit began to inflate and about an hour later the amplitude of tremor and the rate of long-period earthquakes began to decline for about 2 hours. The inflation ended at about 1000, regaining up to 2.5 microradians at the summit. By 9 April surface lava flows traveled down Pulama Pali, seismic activity returned to normal levels, and all tiltmeters showed flat signals.
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.