Report on Kilauea (United States) — July 1994
Bulletin of the Global Volcanism Network, vol. 19, no. 7 (July 1994)
Managing Editor: Richard Wunderman.
Kilauea (United States) Bench collapses and littoral explosions occur as lava flows continue to enter the ocean
Please cite this report as:
Global Volcanism Program, 1994. Report on Kilauea (United States) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 19:7. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199407-332010.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
"The . . . eruption continued throughout July with more lava entering the ocean in the W Kamoamoa/Lae Apuki area. On the morning of 8 July, a piece of the Kamoamoa bench, ~4,000 m2, fell into the ocean. Littoral explosions following the collapse deposited a small amount of spatter on the delta. A wave associated with the collapse event deposited blocks on the surface of the delta, 40 m inland of the sea cliff. One line of stations, set up to monitor movement of cracks on the active bench, disappeared into the ocean with the collapse. Following the event, the remaining lines recorded several centimeters of seaward movement. The cracks on the bench continued to widen throughout the month. Some of the larger cracks contained standing water.
"Surface activity was confined mostly to the W Kamoamoa/Lae Apuki bench; however, on 11 July, a surface flow broke out of the active tube on Pali Uli. This flow did not reach the ocean before stagnating. There were no significant changes in the Pu`u `O`o lava pond, which was 79 m below the crater rim in July.
"The ocean entries were intermittently explosive, following the 8 July collapse, due to smaller collapses along the front of the bench. Littoral explosions increased in frequency and magnitude later in the month. The most dramatic event began on the afternoon of 26 July. By the following day, large spatter bursts had built a 10-m-high littoral cone on the leading edge of the Kamoamoa/Lae Apuki bench. Explosive activity was initially episodic but was continuous by at least 1810 on 27 July. At 2025 a cascade of lava, about 5 m wide, ripped out of the tube on Pali Uli, from the same area as the 11 July flow. Within 50 minutes, the explosive activity at the ocean had subsided. The cascade on Pali Uli fed flows that eventually stagnated the following day. Activity at the ocean paused briefly, but by 1112 on 28 July, plumes were again visible off the Kamoamoa/Lae Apuki bench. Surface flows broke out on the bench, and by the end of the month extended the bench 5-10 m W."
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: T. Mattox, HVO.