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Report on Kilauea (United States) — December 1989


Kilauea

Scientific Event Alert Network Bulletin, vol. 14, no. 12 (December 1989)
Managing Editor: Lindsay McClelland.

Kilauea (United States) Two ocean entries remain active; littoral explosions

Please cite this report as:

Global Volcanism Program, 1989. Report on Kilauea (United States) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 14:12. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198912-332010



Kilauea

United States

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

All times are local (unless otherwise noted)


Throughout December, lava from Kupaianaha pond continued to flow into the ocean . . . (figure 64). Most of the lava (75-95%) entered the water at the Poupou entry, the rest at the October entry on the Kailiili delta, now designated the W Kailiili entry (figure 65). The output at W Kailiili had diminished to a trickle by the end of December.

The Poupou lava tube branched near the coastline and, during most of the month, terminated in two streams of lava, 25-50 m apart at the waterline. Intermittent littoral explosions added spatter and limu to the large 2-3-m littoral cone atop the sea cliff. Two smaller cones formed in early December ~20 m to the E. They were nearly buried at mid-month by a surface flow that emerged from the tube near the ocean and cascaded over the sea cliff to form a 30 x 10 m bench. This flow stagnated within a few days. As the surface flow emerged, an inflated area ~3 m high by 15-20 m in diameter formed behind the large cone.

Breakouts from the lava tube system at 550-480 m elevation (1,850-1,600 ft) produced small pahoehoe flows that encroached on the kipukas along the W flow margin. At the 180 m (600 ft) level, breakouts fed small flows that terminated 300-400 m upslope of the Royal Gardens kipuka through the 18th. Surface breakouts in Royal Gardens were first reported on 11 December. On 6 December, a thin flow encroached on the S half of the Wahaula Heiau (temple) grounds. One lobe of the flow stagnated ~10 m N of the ruins, but most lava flowed farther E and cascaded over the sea cliff onto the new black sand beach below. Activity of the Wahaula flow ceased after 8 December.

The level of Kupaianaha lava pond, which had dropped to ~30 m below the rim in November, remained low and stable in December. Glowing vents at the bottom of Pu`u `O`o were reported on the 3rd and 11th, but no active lava was present.

Low-level tremor continued . . . near Pu`u `O`o and Kupaianaha. Above the background of continuous tremor, high-frequency microshocks associated with minor crustal fracturing around Kupaianaha were detected by the Kalalua seismometer, ~1 km away. The number of shallow (<5 km) microearthquakes was about average in the summit region and the East rift zone. Intermediate-depth (5-15 km) long-period events continued, reaching several hundred/day. A widely felt earthquake (preliminary M 5.1) struck the S flank of Kīlauea at 2313 on 27 December at 9 km depth.

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.