Report on Kilauea (United States) — May 1987
Scientific Event Alert Network Bulletin, vol. 12, no. 5 (May 1987)
Managing Editor: Lindsay McClelland.
Kilauea (United States) Lava enters ocean from underwater tubes and surface flows
Please cite this report as:
Global Volcanism Program, 1987. Report on Kilauea (United States). In: McClelland, L. (ed.), Scientific Event Alert Network Bulletin, 12:5. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198705-332010.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
The primary activity . . . in May and early June was a slow advance of dense pahoehoe continually overriding older flows. By mid-May the lava . . . was completely within tubes, with some minor breakouts . . . at 150-20 m elevation late in the month. Low-volume lava flows entered the ocean 11-18 May. On 17 May, divers reported lava issuing from tube openings ~10 m underwater. Occasional lava extrusions along the tube system fed flows that overran > 30 m of Hwy 130 on 29 May and 2 June, buried more of Pacific Paradise Ocean Front Estates (partially overrun in November 1986) and again entered the ocean on 4 June. More than 1.8 km of the Chain of Craters Road has been covered with lava.
The level of the lava pond over the vent at 670 m elevation varied from as much as 9 m below the rim to vigorous overflows on 30 May. Tumescence followed by intermittent breakouts of pahoehoe and aa occurred in the shield's N flank, forming short flows.
The summit tiltmeter showed minor fluctuations but indicated no long-term trend of inflation or deflation. Harmonic tremor persisted . . . near the eruptive vent. Bursts of relatively high-amplitude tremor lasting 5-20 minutes occurred at irregular intervals of less than an hour to many hours during the week of 6-13 May and again in early June. The number of microearthquakes was slightly above average in the summit and East rift zone. Earthquakes of M 2.5-3.5 were concentrated on the S flank of Kilauea and the Kaoiki fault region at 5-10 km depth.
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.
Information Contacts: C. Heliker and R. Koyanagi, HVO.