Report on Kilauea (United States) — 6 August-12 August 2003
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
6 August-12 August 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, 6 August-12 August 2003. Smithsonian Institution and US Geological Survey.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
Surface lava flows were visible on Kilauea's coastal flat and at several areas upslope during 6-12 August. Deflation that began on 8 August amounted to about 1.8 microradians at Uwekahuna tiltmeter and 4 microradians at Pu`u `O`o tiltmeter, both located at the volcano's summit. The deflation was accompanied by a drop in the level of lava in a lava tube, as seen by field workers at midday. Then, inflation began later that day at 1928, and in ~3.5 hours there was ~3.5 microradians of inflation at Uwekahuna and ~6 microradians at Pu`u `O`o. A lava breakout occurred on 9 August between 0200 and 0300, about 1.3 km SE of the center of Pu`u `O`o cone. A very large sheet flow emerged from a point on the uptube side of a rootless shield that was formed on 21 January. Observers saw a lava stream, up to 40 m wide. By 0600 the area of the flow was about 5.2 hectacres (0.052 square km). During the report week, seismicity at Kilauea's summit continued at moderate levels, with many small, low-frequency earthquakes continuing at shallow depths beneath the summit caldera every 1-2 minutes. During the deflation on 8 August, there was an increase in such earthquakes and changes in their frequency content. Some larger events occurred at depths of a few kilometers, as had been the case during the previous several weeks
Geological Summary. Kilauea overlaps the E flank of the massive Mauna Loa shield volcano in the island of Hawaii. Eruptions are prominent in Polynesian legends; written documentation since 1820 records frequent summit and flank lava flow eruptions interspersed with periods of long-term lava lake activity at Halemaumau crater in the summit caldera until 1924. The 3 x 5 km caldera was formed in several stages about 1,500 years ago and during the 18th century; eruptions have also originated from the lengthy East and Southwest rift zones, which extend to the ocean in both directions. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1,100 years old; 70% of the surface is younger than 600 years. The long-term eruption from the East rift zone between 1983 and 2018 produced lava flows covering more than 100 km2, destroyed hundreds of houses, and added new coastline.