Report on Kilauea (United States) — 29 August-4 September 2012
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 29 August-4 September 2012
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2012. Report on Kilauea (United States). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 29 August-4 September 2012. Smithsonian Institution and US Geological Survey.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
During 28 August-4 September HVO reported that the circulating lava lake periodically rose and fell in the deep pit within Kilauea's Halema'uma'u Crater. The gas plume from the vent continued to deposit variable amounts of spatter and Pele's hair onto nearby areas. On 28 August two major collapses of the inner wall significantly disrupted the lake's circulation.
Lava flows were periodically active on the pali and the coastal plain. At Pu'u 'O'o, a collapse of the crater floor just before 0400 on 30 August enlarged the newer pit crater at the S edge, making it appear slightly larger in the webcam views than the older, active, pit crater on the E edge. A new pit crater formed at the N edge of the floor after 1000, and by 1300 it was filled with lava. The N rim of the E pit crater fell into the lava lake there just before 1700. During 30-31 August incandescence emanated from the lava lake in the E pit crater but was absent from the S pit crater. A few scattered areas of flow activity on the coastal plain more than 2 km from the coast were visible on web cameras. On 1 September glow emanated from the E and S pit craters. Crusted lava filled the N pit crater and sagged, and a couple of small lava flows traveled from the edge onto the sagging crust. The N pit appeared to be a passive lava lake, without a direct source of magma underneath. A collapse in the roof of the lava tube at the base of the SE flank of Pu'u 'O'o continued to glow but was less bright the next day.
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.