Report on Kilauea (United States) — 25 March-31 March 2015
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 25 March-31 March 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, 25 March-31 March 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 25-31 March HVO reported that Kilauea’s 27 June NE-trending lava flow continued to be active with four separate breakouts in three areas within and along the flow-field margins. 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 (burning trees were visible), and a relatively small breakout 5-6 km farther NE of Pu'u 'O'o. On 25 March HVO lowered the Volcano Alert Level from Warning to Watch, noting that in recent weeks the Pu'u 'O'o lava flows nearest to the town of Pahoa were inactive. The Aviation Color Code remained at Orange. The circulating lava lake occasionally rose and fell in the deep pit within Halema'uma'u Crater. Gas emissions remained elevated.
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.