Report on Kilauea (United States) — March 1984
Scientific Event Alert Network Bulletin, vol. 9, no. 3 (March 1984)
Managing Editor: Lindsay McClelland.
Kilauea (United States) Episodes 16 and 17 include strong fountaining, tephra, and the longest flow of the 1983-84 eruption
Please cite this report as:
Global Volcanism Program, 1984. Report on Kilauea (United States) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 9:3. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198403-332010.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
"The 16th and 17th major episodes of the eruption occurred 3-4 and 30-31 March. Pu'u O was the eruptive locus for both episodes. Simultaneous eruptions on 30 March at Mauna Loa, Mt. St. Helens, Veniaminof, and Kilauea make this the first date known on which four U.S. volcanoes were erupting at the same time.
"Beginning on 28 February, lava was visible continuously within the upper 30 m of the vertical 20 m-diameter pipe that extended downward from the bowl-like crater within Pu'u O. Sometimes completely open and sometimes partly crusted, the surface of the magma column rose slowly over the next 4 days to the level of the spillway in the deep breach in the NE rim of Pu'u O. Minor amounts of spatter and small volumes of SO2-rich gas issued from the lava surface.
"Time-lapse camera data indicate that the lava ponded within Pu'u O first overflowed the spillway on 3 March at about 1450. The vigor of fountain activity increased from that time, and the fountain became visible above the rim of Pu'u O at about 1520. By 1700, when HVO personnel arrived, the fountain rose 200-250 m above the lava pond (the crater rim was about 40 m above the pond). Glowing tephra was at times wafted to twice the height of the fountain by convective air currents rising over the cone. Erratic winds distributed tephra on all sides of the vent and at times during the night, intense tephra falls, including incandescent bombs up to 20 cm in diameter, rained on observers 750 m uprift of the vent. At about 0400 on 4 March, fountain activity diminished greatly and became sporadic. During the remainder of the eruption the fountain played to heights ranging from about 20-150 m above the pond.
"The intense fountain activity produced a thick spatter-fed aa flow that advanced about 1 km N; smaller spatter-fed flows extended E, SE, and W. The major flow, dominantly aa, was fed by a vigorous lava river debouching through the breach in the NE rim of Pu'u O at an average of about 0.25 x 106 m3/hour. It advanced E and ESE, mostly on top of flows from earlier episodes. Approximately 6.4 km from the vent, it split into 2 lobes, the longer of which extended another 1.6 km SE across the NE corner of Royal Gardens subdivision. This lobe, however, was contained within the evacuated channel of the episode 2 flow that invaded the subdivision in March 1983, and caused no new damage. After a momentary pause at 2228, the eruption stopped abruptly at 2231 on 4 March. Occasional small bursts of spatter issued from the vent over the next 10 or 15 minutes.
"Basalt produced during episode 16, as in previous episodes, is sparsely porphyritic. In hand specimen, scattered, small (millimeter-size) olivine phenocrysts are visible. Lava temperatures, measured by thermocouple, were 1,139-1,142°C in pahoehoe within 1.5 km of the vent and 1,135-1,138°C at the advancing distal end of the main flow in aa and local breakouts of viscous pahoehoe.
"The volume of lava erupted during episode 16 was approximately 12 x 106 m3. The corresponding summit collapse caused almost 15 µrad of deflationary tilt change at Uwekahuna. As in previous episodes, the beginning and end of measurable summit deflation lagged slightly behind the onset and termination of lava production at the vent.
"Harmonic tremor associated with episode 16 began to increase gradually in amplitude on 3 March at 1435, and rapid increase began at 1504. Sustained, high-level tremor continued in the eruption area until 4 March at 2229 when the intensity began to pulsate and gradually decrease. Rapid decrease in tremor amplitude began at 2231, coincident with the end of lava production.
Repose-period activity. "The repose period between episodes 16 and 17 was marked by an unusually gradual reinflation of the summit, slightly over 9 µrad of inflationary tilt change in 3½ weeks. The upper surface of the gradually rising magma column was first seen at the vent on 20 March, when it was approximately 50 m deep inside the pipe that extends downward from the crater floor, and 60 m below the spillway through the NE crater rim. Intermittent observations showed that the column rose slowly until the onset of vigorous lava production on 30 March.
"Harmonic tremor related to episode 17 began to increase 30 March at 0510, and glow from the eruptive area was visible from Kilauea's summit at 0515. A photographer camped near the vent reported seeing a low dome fountain in the crater and a short NE-moving lava flow at about 0520-0530. He estimated that the flow was about 0.5 km long by 0545, and that by about 0610 the fountain top was at the level of the rim of Pu'u O (about 40 m above the surface of the overflowing lava pond).
"HVO personnel arrived at about 1000. From then on, they observed the fountain playing in a rapidly pulsating fashion (up to 20 pulses per minute); the fountain height ranged about 40-160 m above the surface of the lava pond. A narrow lava flow, fed by a voluminous lava river discharging through the breach in the NE crater rim, was more than 1.5 km long at 1000. It extended ENE (to the spatter/cinder cone south of Pu'u Kahaualea) then, following the episode 16 flow, turned ESE. During the day the flow continued advancing ESE on top of the episode 16 flow at 0.5 km/hour. During the night it followed the northern episode 16 lobe N of Royal Gardens. Near the terminus of that episode 16 lobe, the episode 17 flow turned SE and followed a gully parallel to and 1 km NE of the subdivision's E boundary. When seen the next morning, 3.5 hours after the eruption's end, the still-advancing aa flow front was about 3 km from the ocean. A preliminary estimate suggests that this flow is more than 10 km long, the longest of the 1983-84 eruptive series. Episode 17 stopped on 31 March at 0324. The sustained high-amplitude tremor characteristic of Pu'u O eruptions began to diminish in intensity at 0316 and by 0324, when lava production stopped, the tremor amplitude had nearly reached the repose-period background level.
"The episode 17 basalt, like the episode 16 basalt, is slightly porphyritic with scattered millimeter-size olivine phenocrysts. However, thermocouple temperatures measured in overflows at the edge of the lava river range from 1,131 to 1,137°C, distinctly lower than the episode 16 temperatures.
"Measurable summit deflation began about 2.5 hours after the onset of lava production and ended nearly 4 hours after the termination of lava production. Deflationary tilt change at Uwekahuna was about 10 µrad. A preliminary guess is that the volume of episode 17 lava is significantly 1ess than the episode 16 volume."
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: E. Wolfe, A. Okamura, R. Koyanagi, HVO.