Report on Kilauea (United States) — 13 May-19 May 2015
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 13 May-19 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, 13 May-19 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)
HVO reported that the circulating lava lake in the pit within Kilauea's Halema'uma'u Crater started to drop on 9 May and as of 15 May was about 50 m lower than the raised vent rim. The lake-level drop was accompanied by a change from inflation of the summit area to deflation centered near Halema'uma'u Crater. In addition, on 13 May, the focus of deformation changed to the S part of Kilauea's summit caldera and upper Southwest Rift Zone (SWRZ), where rapid and localized inflationary tilt was recorded. Seismicity shifted from Kilauea's summit and the upper East Rift Zone (ERZ) to the S part of the summit; seismicity at the upper SWRZ continued. The number of earthquakes increased on 15 May. The data suggest that magma had moved into a shallow area beneath the S part of the caldera and upper SWRZ. During 16-18 May rates of tilting slowed, and seismicity at the summit and SWRZ remained above background levels but had decreased. By 19 May seismicity rates at the summit were normal and tilit had decreased slightly. The lava lake remained about 45-50 m below the crater floor.
Nighttime incandescence suggested an active lava pond in an isolated vent W of Pu'u 'O'o Crater. The June 27th NE-trending lava flow continued to have active surface flows within 8 km NE of Pu'u 'O'o.
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.