Report on Kilauea (United States) — September 1997
Bulletin of the Global Volcanism Network, vol. 22, no. 9 (September 1997)
Managing Editor: Richard Wunderman.
Kilauea (United States) Lava effusion and overflows
Please cite this report as:
Global Volcanism Program, 1997. Report on Kilauea (United States). In: Wunderman, R. (ed.), Bulletin of the Global Volcanism Network, 22:9. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199709-332010.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
Since mid-August, eruptive activity has been concentrated at a vent on the Pu`u `O`o crater floor and at the S shield, a new lava shield ~300 m S of the Pu`u `O`o cone. Lava continuously effused from a spatter cone inside Pu`u `O`o crater during 17 August-23 September. The flows caused occasional overflows of a lava pond in the E part of the crater, and sometimes disappeared into cracks on the crater floor. A voluminous 6 August overflow (BGVN 22:07) produced 1.2-km-long pahoehoe flows; eruption rates were estimated at 100,000- 900,000 m3/day. Lava flows also occurred at a small vent on the S shield; these flows fed lava tubes leading to the coast, where lava entered the sea at Waha`ula and Kamokuna (figure 113).
|Figure 113. Map of recent lava flows from Kilauea's east rift zone, 21 October 1997. Contours are in meters and the contour interval is approximately 150 m. Courtesy of the USGS Hawaiian Volcano Observatory.|
During 28 September-3 October flows from the S shield vent moved within lava tubes. Lava was only visible through occasional skylights in the tube's roof and during two brief episodes when lava escaped onto the coastal plain. During this time eruption rates were ~500,000 m3/day. The Pu`u `O`o spatter cone subsided, creating an ~40- m-diameter pit that was the source of lava issuing into the crater. On 28 September a lava overflow fed a small flow that moved a few meters W and a few tens of meters E of the crater rim.
On 18-19 October another lava overflow episode at Pu`u `O`o resulted in flows from the low points in the E and W rims of the crater beginning at 0400. By the evening of 19 October, the flows had created broad areas of incandescent lava whose glow was visible up to 45 km away. Lava flow in the ocean-bound tubes was reduced to a trickle and steam plumes at the sea entry sites disappeared at 1200 on 18 October but resumed the next morning.
Sulfur dioxide gas emission from the Pu`u `O`o vents increased from 1,000-1,500 tons/day on 2 October to 1,500-2,000 tons/day by 21 October.
Kilauea is one of five coalescing volcanoes that comprise the island of Hawaii. Historically its eruptions originate primarily from the summit caldera or along one of the lengthy E and SW rift zones that extend from the summit caldera to the sea. This latest Kilauea eruption began in January 1983 along the E rift zone. The eruption's early phases, or episodes, occurred along a portion of the rift zone that extends from Napau Crater on the uprift (towards the summit) end to ~8 km E on the downrift (towards the sea) end. Activity eventually centered on what was later named Pu`u `O`o. Between January 1983 and December 1996, erupted lava totaled ~1.45 km3.
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: Hawaiian Volcano Observatory (HVO), U.S. Geological Survey, PO Box 51, Hawaii Volcanoes National Park, HI 96718, USA (URL: https://volcanoes.usgs.gov/observatories/hvo/); Ken Rubin and Mike Garcia, Hawaii Center for Volcanology, University of Hawaii, Dept. of Geology & Geophysics, 2525 Correa Rd., Honolulu, HI 96822 USA (URL: http://www.soest.hawaii.edu/GG/hcv.html).