Report on Kilauea (United States) — December 1984
Scientific Event Alert Network Bulletin, vol. 9, no. 12 (December 1984)
Managing Editor: Lindsay McClelland.
Kilauea (United States) Episodes 28 and 29 are one-day eruptions with fountains to 450 m
Please cite this report as:
Global Volcanism Program, 1984. Report on Kilauea (United States) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 9:12. Smithsonian Institution.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
"Episode 28 began at 1905 on 3 December. High fountaining and continuous lava production lasted for 14.5 hours, ending at 0941 on 4 December. The lava spilled over the broad NE rim of the cone (Pu'u O) and produced a broad short aa fan to the NE and two larger aa flows to the SE. The SE flows extended 4.7 km from the vent, ending about 1.2 km short of Royal Gardens subdivision. The high fountains were accompanied by heavy tephra fallout in a broad swath downwind of the vent. Episode 28 produced 12.3 x 106 m3 of lava and approximately 0.2 x 106 m3 of tephra (lava equivalent).
"Pu'u O was in repose for the remainder of the month. On 30 December, low fountains (3-10 m) produced thin pahoehoe overflows that reached the base of the cone. Similar activity occurred intermittently for the next 4 days until high fountains and continuous lava production signaled the start of episode 29.
Deformation. "Summit subsidence began at about 1900 on 3 December, at the start of episode 28. The Uwekahuna tiltmeter recorded continuous summit deflation until 1330 the next day, resulting in a net tilt change of 15.9 µrad. During the rest of the month the summit tilt recovered 17.7 µrad.
Seismicity. "Harmonic tremor associated with episode 28 at Pu'u O started to increase gradually at 1815 on 3 December. By 1905 tremor recorded at the Kamoamoa seismic station increased to a level characteristic of high lava fountaining. High-amplitude tremor continued for nearly 15 hours. The sharp decrease in tremor following the end of the eruptive episode was recorded at 0941 on 4 December. For the rest of December, tremor was at low levels, varying from the fluctuating amplitude associated with gas-pistoning activity at Pu'u O, to continuous amplitude with no visible lava activity.
Addendum: The current Kilauea eruption sequence celebrated its 2nd anniversary on 3 January 1985 with the start of episode 29. Fountains up to 460 m high fed aa flows to the NE and SE during the 16 hour episode.
Geological Summary. 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, A. Okamura, G. Ulrich, HVO.