Report on Kilauea (United States) — 29 April-5 May 2009
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 29 April-5 May 2009
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2009. Report on Kilauea (United States) (Sennert, S, ed.). Weekly Volcanic Activity Report, 29 April-5 May 2009. Smithsonian Institution and US Geological Survey.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
During 29 April-5 May, HVO reported that lava flowed SE from underneath Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex through a lava tube system, reaching the Waikupanaha and Kupapa'u ocean entries. Some explosions occurred at the Waikupanaha ocean entry. The vent in Halema'uma'u crater continued to produce a white plume that sometimes caused poor air quality in nearby areas. Sounds resembling rushing gas were sometimes heard in the vicinity of the crater. Various amounts of tephra, spatter, and ash were retrieved from collection bins placed near the plume during the reporting period. On 3 May, unusually bright incandescence seen from the vent on the web camera was accompanied by a decrease in summit tremor levels of about 40 percent. During 4-5 May, bright incandescence was again noted; summit tremor levels were variable but never exceeded moderate values.
Geological Summary. Kilauea overlaps the E flank of the massive Mauna Loa shield volcano in the island of Hawaii. Eruptions are prominent in Polynesian legends; written documentation since 1820 records frequent summit and flank lava flow eruptions interspersed with periods of long-term lava lake activity at Halemaumau crater in the summit caldera until 1924. The 3 x 5 km caldera was formed in several stages about 1,500 years ago and during the 18th century; eruptions have also originated from the lengthy East and Southwest rift zones, which extend to the ocean in both directions. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1,100 years old; 70% of the surface is younger than 600 years. The long-term eruption from the East rift zone between 1983 and 2018 produced lava flows covering more than 100 km2, destroyed hundreds of houses, and added new coastline.