Report on Kilauea (United States) — 12 December-18 December 2012
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 12 December-18 December 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, 12 December-18 December 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 12-18 December HVO reported that on most days the circulating lava lake periodically rose and fell in the deep pit within Kilauea's Halema'uma'u Crater. Occasional measurements indicated that the gas plume from the vent continued to deposit variable amounts of ash, spatter, and Pele's hair onto nearby areas.
At Pu'u 'O'o Crater, glow emanated from spatter cones on the SE part of the crater floor, from a spatter cone at the NW edge of the floor, and from a lava lake on the NE part of the floor which was mostly covered by a spatter cone. The lava lake overflowed during 12-13 December, and on 13 December lava flowed from the SW spatter cone. On 14 December the N rim of the NE spatter cone/lava lake collapsed and was followed by a brief overflow of the lake. A larger lava flow issued from a spatter cone on the N edge of the crater floor, followed by another smaller flow; both flows traveled W, then split and flowed N and S. Another rim collapse from the NE spatter cone/lava lake and small overflow were observed the next day.
Lava flows remained active in two branches on the coastal plain: a small W branch, and a larger E branch with scattered activity extending from the pali to the coast E of the easternmost boundary of Hawai'i Volcanoes National Park. An ocean entry was marked by a weak and variable plume near Kupapa'u, with lava entering the water in at least two different areas. A new lava flow at the top of the pali was observed on 11 December. On 15 December observers noted that lava flows were active in a 1-km-wide area that stretched from near the base of the pali to the coast. On 16 December HVO noted that a lava delta at the ocean entry had slowly grown to be 50 m wide.
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.