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Report on Kilauea (United States) — June 1983


Kilauea

Scientific Event Alert Network Bulletin, vol. 8, no. 6 (June 1983)
Managing Editor: Lindsay McClelland.

Kilauea (United States) Lava flows and spatter cones produced by two new phases of E rift zone eruption

Please cite this report as:

Global Volcanism Program, 1983. Report on Kilauea (United States) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 8:6. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198306-332010



Kilauea

United States

19.421°N, 155.287°W; summit elev. 1222 m

All times are local (unless otherwise noted)


EPISODE 4

"The fourth and fifth major episodes of Kīlauea's E rift zone eruption occurred during June and early July. The two eruptive events, each about 4 days long, produced three new major lava flows that extended SE down the S flank.

"The eruptive vent for both episodes was located just within the Hawaii Volcanoes National Park about 750 m NE of Pu'u Kamoamoa (figure 19). The same vent had been active intermittently since early January; in late March it produced a 5-km-long lava flow that extended SE along the National Park boundary.

Figure (see Caption) Figure 19. Distribution of Kīlauea lavas and vent deposits for phases 1-7, January-August 1983.

"Episode 4 lava fountains were first reported from a passing aircraft at 1025 on 13 June. When the first ground observers arrived at midday, a line of low fountains about 100 m long was feeding flows to both the NW and SE. The NE end of the vent quickly became the major locus of lava production, and an aa flow fed by a vigorous river of pahoehoe began extending SE, on top of and adjacent to the late March (episode 3) flow. A steep-sided spatter cone 30-40 m high was built at the source of the flow, which cascaded over a spillway one-half to two-thirds of the way up the S side of the cone. A low fountain, up to about 20 m high, played from the surface of the lava pond that filled the interior of the cone to the level of the spillway.

"Lava discharge was estimated at about 100,000 m3/hour. The main flow extended about 7.5 km SE from the vent and covered approximately 1.5 x 106 m2. Its front advanced at about 30-200 m/hour. Following the National Park boundary, the flow entered Royal Gardens subdivision only locally, and no homes were destroyed. Episode 4 ended abruptly at 1413 on 17 June, a little more than 4 days after it began.

"Like previous 1983 lavas, episode 4 basalt is slightly porphyritic, with scattered small phenocrysts of plagioclase and olivine. Lava temperatures, measured by thermocouple, ranged from 1,115 to 1,132°C.

EPISODE 5

"Episode 5 began on 29 June. At 1000, a pool of lava was seen slowly rising inside the main episode 4 vent. At about 1300 lava production became vigorous, and episode 5 lava cascaded over the earlier spillway and began flowing SE within the previously evacuated episode 4 channel. Lava production quickly reached and was maintained at a rate similar to that of episode 4, approximately 100,000 m3/hour, and an aa flow began advancing SE over episode 3 and 4 basalts. The flow was fed by a vigorous pahoehoe channel that was generally bank-full and frequently overflowing. Advancing at average rates ranging from 80-165 m/hour, the flow front entered the NW part of Royal Gardens subdivision at 1919 on 1 July. It finally stopped 8 km from the vent at about 1030 on 3 July, more than 3 hours after the vent had stopped erupting. Traversing the subdivision, it burned and crushed 7 dwellings and cut off 4 others from road access. The average velocity of the flow moving down the 4-8° slopes of the subdivision was 56 m/hour, but the actual velocity ranged from 0-30 m/min. Periods of stagnation up to a few hours long alternated with rapid surges that advanced the flow front by 100-300 m in 30 minutes.

"At about 1600 on 29 June a satellite vent on the W flank of the main vent began erupting. For the next 24 hours it supplied local pahoehoe flows that extended about a kilometer N and NE of the vent. Then, in mid to late afternoon of 30 June, the satellite vent stopped feeding flows to the north and began to feed an aa flow that extended 5 km SE along the SW edge of the episode 3 and 4 flows. It, too, was fed by a pahoehoe channel; the front of this flow advanced at average rates of 70-110 m/hour.

"Fountain activity at the episode 5 vents constructed a pair of juxtaposed spatter cones about 40 m high. Lava pond surfaces within the 2 vents were 20-30 m above the bases of the cones. Fountains played from the ponds, and spatter was ejected to maximum heights of about 50 m above the pond surfaces. Fountaining was more vigorous than in episode 4, which suggested that the episode 5 magma may have been less depleted in gas. Lava production at the vents stopped at 0717 on 3 July, nearly 4 days after the eruption began.

"Thermocouple measurements gave lava temperatures of 1,127-1,129°C. Basalt collected near the end of episode 5 may be compositionally different from lavas erupted in previous episodes. Millimeter-size olivine phenocrysts are abundant, and plagioclase phenocrysts are rare. Unfortunately, no temperature measurements are specifically correlated with these samples.

Deformation and seismicity. "Water-tube tilt measurements in the summit region (at Uwekahuna) showed small but distinct periods of summit deflation that correlated with episodes 4 and 5. Minimum volume loss at the summit was estimated to be about 14 x 106 m3 for episodes 4 and 5 combined. Cumulative deflation since early January was approximately 235 µrad; a minimum volume loss at the summit of about 95 x 106 m3 is suggested.

"Very low-level harmonic tremor has characterized the periods between eruptive episodes. On 13 June, approximately coincident with the onset of episode 4, tremor increased from 0500 to about 1100. It remained constantly high until 17 June, when it declined rapidly from 1400-1600. Again, coincident with episode 5, tremor amplitude increased beginning at about 0900 on 29 June. It stayed high through the eruption, and, in concert with the end of lava production, the tremor dropped dramatically from 0713-0720 on 3 July."

Robert Symonds measured a rate of SO2 emission from Kīlauea of 8000 t/d from the ground on 30 June and the same flux from the air on 1 July.

Geological Summary. Kilauea overlaps the E flank of the massive Mauna Loa shield volcano in the island of Hawaii. Eruptions are prominent in Polynesian legends; written documentation since 1820 records frequent summit and flank lava flow eruptions interspersed with periods of long-term lava lake activity at Halemaumau crater in the summit caldera until 1924. The 3 x 5 km caldera was formed in several stages about 1,500 years ago and during the 18th century; eruptions have also originated from the lengthy East and Southwest rift zones, which extend to the ocean in both directions. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1,100 years old; 70% of the surface is younger than 600 years. The long-term eruption from the East rift zone between 1983 and 2018 produced lava flows covering more than 100 km2, destroyed hundreds of houses, and added new coastline.

Information Contacts: E. Wolfe, A. Okamura, and R. Koyanagi, USGS HVO, HI; R. Symonds and T. Casadevall, USGS CVO, Vancouver WA.