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Report on Kilauea (United States) — June 1982


Kilauea

Scientific Event Alert Network Bulletin, vol. 7, no. 6 (June 1982)
Managing Editor: Lindsay McClelland.

Kilauea (United States) Intrusion into the SW rift

Please cite this report as:

Global Volcanism Program, 1982. Report on Kilauea (United States) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 7:6. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198206-332010



Kilauea

United States

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

All times are local (unless otherwise noted)


Summit deflation and an earthquake swarm in the SW rift marked Kīlauea's 16th intrusive event since the magnitude 7.2 earthquake of November 1975. A continuously recording tiltmeter high on the NW flank began to show deflation during the night of 21-22 June, and seismographs detected the gradual onset of earthquakes in the middle SW rift early 22 June. Low-level harmonic tremor began about 1800. Deflation reached its maximum rate of 1.05 µrad/hour (E-W component) between 2100 and 2200 on 23 June, then gradually decreased. By 0900 on the 24th, tremor had generally ceased. Deflation had nearly stopped by 2200 and the number of microearthquakes had dropped from a maximum of a few hundred per hour to about 1 every 2 minutes.

Early in the swarm, earthquakes were concentrated at 7-8 km depth about 10 km SW of the summit caldera (in the Koae fault system about 3 km S of Pu'u Koae). No significant downrift migration of the epicenters occurred. About 50 µrad of summit deflation (E-W and N-S tilt recalculated to N60°W) were recorded during the intrusion (figure 6). Roughly 20 x 106 m3 of magma were injected into the SW rift, about half the volume of the last SW rift intrusion in August 1981. During Kīlauea's 30 April-1 May 1982 eruption, about 0.5 x 106 m3 of lava flowed onto the caldera floor.

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: Hawaiian Volcano Observatory, USGS.