Report on Kilauea (United States) — 22 April-28 April 2015
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 22 April-28 April 2015
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2015. Report on Kilauea (United States). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 22 April-28 April 2015. Smithsonian Institution and US Geological Survey.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
During 22-28 April HVO reported that Kilauea’s 27 June NE-trending lava flow continued to be active with three areas of breakouts within and along the flow-field margins, within 8 km of Pu'u 'O'o. The three main areas of breakouts were the 21 February breakout on the flank of Pu'u 'O'o, the 9 March breakout near the forested cone of Kahauale'a, and a relatively small forked breakout 5-6 km farther NE of Pu'u 'O'o. Forest burned about 8 km NE of the crater. The thermal webcam recorded multiple incandescent outgassing vents in the crater. Lava that sporadically erupted from vents on the SE and S parts of Pu'u 'O'o's crater floor covered the floor.
The circulating lava lake occasionally rose and fell in the deep pit within Halema'uma'u Crater. Gas emissions remained elevated. Abrupt inflation began at 1640 on 21 April; concurrently the lava lake rose and was 20 m below the crater floor on 23 April, the highest level since the eruption began in 2008. A small collapse from the overhanging W wall at about 0520 triggering a small explosive event that ejected spatter out onto the Halema'uma'u crater floor. The lake continued to rise and was 12 m below the floor on 25 April. Two collapses of the W crater wall each triggered explosions that ejected clumps of spatter (some 30 cm in diameter) up onto the rim of Halema'uma'u and dusted the Jaggar Museum area with ash. During 25-26 April the lava lake rose to within about 4 m of the crater floor. During 27-28 April the lava lake fluctuated but was mostly 3-4 m below the rim, and briefly reached the rim on 28 April at a time without spattering.
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.