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Report on Kilauea (United States) — February 1989


Kilauea

Scientific Event Alert Network Bulletin, vol. 14, no. 2 (February 1989)
Managing Editor: Lindsay McClelland.

Kilauea (United States) Lava enters sea through tubes; surface breakouts upslope

Please cite this report as:

Global Volcanism Program, 1989. Report on Kilauea (United States) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 14:2. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198902-332010



Kilauea

United States

19.421°N, 155.287°W; summit elev. 1222 m

All times are local (unless otherwise noted)


The . . . eruption continued during February with the source remaining the Kupaianaha lava pond (filled with lava to 20-25 m below its rim). About 80% of the lava that entered the ocean traveled through the W branch of the tube system. Frequent surface breakouts at ~300 m elevation produced small pahoehoe flows that moved over older lava. One reached 200 m elevation on the 22nd before stagnating. Flows produced by surface activity from the smaller central tube during the first week in February had stopped by the 8th. The terminus of the E tube remained stagnant above Highway 130, but outbreaks upslope from 350 to 400 m elevation fed sluggish flows until the 10th. The seacoast lava bench continued to grow after the large 23 January collapse. On 12 February, a 160-m-long edge of the older portion of the bench collapsed. The collapse was [seismically] registered . . . as a series of rockfalls and acoustic signals. On 15 February, the bench measured ~315 x 30 m and it continued to grow through the month.

Tremor . . . was generally steady in amplitude except during occasional rockfalls at Pu`u `O`o. An average number of shallow microearthquakes were detected in the summit area and East rift zone. Intermediate-depth, long-period events beneath the summit increased to ~100 or more/day during the last week of February. Intermittent bursts of deep tremor originated from 40-50 km beneath the summit. Most of the hundreds of earthquakes (M>0.5) processed for location were centered 15 km beneath Kīlauea and Mauna Loa. Eleven large events had magnitudes of 2.5-3.8.

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.

Information Contacts: C. Heliker and R. Koyanagi, HVO.