Report on Kilauea (United States) — May 1986
Scientific Event Alert Network Bulletin, vol. 11, no. 5 (May 1986)
Managing Editor: Lindsay McClelland.
Kilauea (United States) Episodes 45 and 46 of East Rift eruption
Please cite this report as:
Global Volcanism Program, 1986. Report on Kilauea (United States) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 11:5. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198605-332010.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
Episode 45 (E-45). Episode 45 . . . began 7 May at 1645 with typical intermittent lava spillovers. Continuous high fountaining started at 2240, and lava flows exited from both spillways formed during the previous phase. The NE flows extended a maximum of 2 km and those to the SE ~4.5 km, mostly on top of previous flows. Some short flows advanced to the N and NW, forming a broad fan at the base of the cone. The "1123 cone" observation post was again surrounded by flows.
High-amplitude tremor began on 7 May at 2242, almost simultaneously with the loss of 10.8 µrad. By the end of the month, the summit had regained 12.4 µrad of inflation (figure 43).
Episode 46 (E-46). During the afternoon of 1 June intermittent lava fountains were reported at Pu`u `O`o. Continuous fountaining began 2 June at 0230 and ended at 1327. High-amplitude harmonic tremor began at 0240 and declined to background levels at 1309. Summit deflation totaling 11 µrad began on 1 June at 1200 and stopped the next day at 1700, 3.5 hours after lava production ended. Lava flowed through both the NE and SE spillways, extending a maximum of 5 km SE.
A series of very high fountain jets started at 1041, 2¼ hours before the end of the episode. Jetting lasted from several seconds to about a minute, then died back briefly before fountaining resumed. Similar fountain jets were observed during E-42 on 23 February.
After E-46, the summit of Pu`u `O`o was 255 m above the pre-1983 surface, a growth of only 5 m since the end of 1985. The cone was steep and the many short flows on the flanks were widening the base.
Since E-40 on 1 January, the eruption recurrence interval has been very regular, ranging from 22 to 26 days.
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, R. Koyanagi, and R. Hanatani, HVO.