Report on Kilauea (United States) — 29 April-5 May 2015
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 29 April-5 May 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, 29 April-5 May 2015. Smithsonian Institution and US Geological Survey.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
In a special statement on 29 April, HVO reported that beginning at 2140 the night before the lava lake in Kilauea’s Halema'uma'u Crater overflowed it's rim multiple times, sending lobate sheets of pahoehoe as far as 130 m across the crater floor. The report also noted that a few explosions in the lake triggered by falling wall rock had occurred; one at 1020 on 28 April ejected boulders of molten spatter (2 m in diameter) onto the rim of Halema'uma'u Crater, in the vicinity of the closed visitor overlook fence. Spatter also blanketed an area 100 m along the rim and 50 m back. This area had been closed to the public since 2007.
The accumulating lava had built up a rim around the lake that was a few meters above the crater floor. On 30 April the lava-lake surface was about 4 m below the new rim. During 1-2 May the lake level was near or at the rim, and overflowed onto the floor several times. During 2-3 May the lake surface was 3-5 m above the original, pre-flow crater floor. A collapse of a portion of the crater wall at 1320 on 3 May impacted the lake and triggered a small explosion, ejecting fist-sized clasts onto the crater rim. Lava overflowed the rim several times during 4-5 May.
During 29 April-5 May 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.
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.