Report on Kilauea (United States) — February 1987
Scientific Event Alert Network Bulletin, vol. 12, no. 2 (February 1987)
Managing Editor: Lindsay McClelland.
Kilauea (United States) New outbreaks along lava tube system stagnate
Please cite this report as:
Global Volcanism Program, 1987. Report on Kilauea (United States) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 12:2. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198702-332010.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
Most February activity occurred along a tube system SE of the vent that has fed a lava pond and built a small shield . . . since July. The elevation of the pond was ~656 m asl. There was no further flow activity into the NE-trending fissure after 3 February (figure 47). Beginning at ~520 m elevation the first part of the month, breakouts along the tube system gradually migrated downslope. By mid-month, most activity was within a 60 m elevationn range near the 335 m contour, 6 km SE of the lava pond. From the 15th on, there were two concurrent flows, one traveling along the E margin of the 1984 aa flow and the second on top of the 1984 aa, both emanating from the same tube system at ~450 m elevation. The first flow was intermittently active. A new surge of lava advanced on 25-27 February, then stagnated on the 28th at 130 m elevation, < 3 km from the coast.
The 2nd flow had reached 260 m elevation by the 22nd, then ran off the W side of the 1984 aa and traveled down to 130 m through forest and grassland, stagnating on the 24th. Both flows were narrow, low-volume, channeled aa, too small to show on the scale of figure 47. Lava did not directly threaten residents of nearby Royal Gardens subdivision, but started smoky brush fires 23-26 February. Residents along the E edge of the subdivision were evacuated for one day and the County Fire Dept set backfires to protect the homes in the area.
Since 28 February, activity has been limited to pond overflows on the shield, indicating blockage within the tube system. The height of the shield remained ~46 m above the pre-1983 surface and the daily output of lava was estimated to be 500,000 m3/day. There has been no significant change in summit tilt.
Harmonic tremor persisted at low levels . . . near the vent area. The number of microearthquakes remained at a relatively low level in the summit and East rift zone. Earthquake activity was centered mainly along the S flank of Kilauea and the vicinity of the Kaoiki fault (between Kilauea and Mauna Loa). A burst of deep seismicity 60 km N of Keahole Point on the W side of the island started with a M 4.8 event at 1622 on 3 February, followed by 24 aftershocks ranging from M 2.5 to 4.0 over the next three weeks.
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: C. Heliker and R. Koyanagi, HVO.