Report on Kilauea (United States) — June 1993
Bulletin of the Global Volcanism Network, vol. 18, no. 6 (June 1993)
Managing Editor: Edward Venzke.
Kilauea (United States) Ocean entries remain active; bench collapses continue
Please cite this report as:
Global Volcanism Program, 1993. Report on Kilauea (United States) (Venzke, E., ed.). Bulletin of the Global Volcanism Network, 18:6. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199306-332010.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
The . . . eruption continued in June with little change as lava from the active vents continued to erupt directly into the tube system. Lava traveled downslope in the tubes and was visible through many skylights formed by tube-roof collapse. The W tube system . . . continued to feed small surface flows above 60 m elevation. Breakouts on the W side of the flow field had declined by the end of June. The E tube system (Kamoamoa tube) continued transporting lava into the Kamoamoa area (figure 91) . . . . Pieces of the bench, often including newly built littoral cones, frequently sloughed into the ocean. Vigorous littoral explosions usually followed these small collapses.
|Figure 91. Recent lava flows (November 1992-June 1993) from Kilauea in the Kamoamoa delta area, active lava tubes, and ocean entries, June 1993. Courtesy of T. Mattox.|
A lava flow broke out of the Kamoamoa tube on 29 June and quickly traveled 500 m to enter the ocean on the W side of the Kamoamoa delta. This flow was apparently the culmination of a volume surge in the system, which resulted in breakouts all along the active tube. With the exception of this flow, all of the breakouts were short-lived. On 3 July, most of the bench collapsed into the ocean, leaving a small sliver of material attached to the Kamoamoa delta. A new littoral cone formed almost immediately, and lava flows began to construct a new lower bench.
The volume of material erupted fluctuated considerably in June. Flux estimates based on geoelectric measurements over the active tube system were 150,000-250,000 m3/day. The level of lava in the Pu`u `O`o pond also fluctuated. Early in the month, lava was ~84 m below the crater rim; by mid-June, lava in the pond had dropped another 10 m. By the end of the month the lava level in the pond was up to 74 m below the rim.
Eruption tremor . . . persisted at ~2x background into early July. A swarm of shallow long-period events occurred 17-18 June, followed by a flurry of intermediate-depth long-period events on 18-19 June. Counts in both categories were slightly above average. Shallow, long-period microearthquake counts were high 24-27 June, peaking on 24 June with >700 events; counts gradually declined during the following days. Short-period microshocks were low in number beneath the summit and East rift zone. A watertube tiltmeter near the summit recorded several fluctuations in summit tilt, with a slight inflation from 29 June to 5 July.
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 and P. Okubo, HVO.