Report on Kilauea (United States) — 5 November-11 November 2003
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 5 November-11 November 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, 5 November-11 November 2003. Smithsonian Institution and US Geological Survey.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
Tiltmeters located on the NW side of Kileauea's caldera rim (Uwekahuna) and on the NW flank of the active vent along the East rift zone (Pu`u `O`o cone) showed several microradians of radial tilt, but the week's patterns were complex and plagued by instrument problems.
Moderate seismicity at the summit of Kilauea continued. Many small, low frequency earthquakes have taken place at shallow depths beneath the summit caldera. The tiny earthquakes happened at the rate of about 1-2 per minute. As has been typical of the ongoing swarm for the past several weeks, some larger earthquakes also occurred, these coming from depths of a few kilometers. Little or no volcanic tremor accompanied the swarm at the summit. In contrast, as is the norm, volcanic tremor at Pu`u `O`o remained moderate to high.
On 5 November, two small breakouts occurred. The freshly escaping lava was seen on the Kohola arm of the Mother's Day flow just below the top of the steep cliffs called Pulama pali. Observers watching a 30-40 m diameter crater located on the SW side of Pu`u `O`o crater noted a new lava pond, a new lava flow, and a fuming cone-pit. Visits to active flow fields on 7 November resulted in observations of hornitos, a 200-m-wide rootless shield, and the leading edge of 45-m-wide flow.
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.