Report on Kilauea (United States) — April 1988
Scientific Event Alert Network Bulletin, vol. 13, no. 4 (April 1988)
Managing Editor: Lindsay McClelland.
Kilauea (United States) Lava production resumes after a one-week hiatus
Please cite this report as:
Global Volcanism Program, 1988. Report on Kilauea (United States). In: McClelland, L. (ed.), Scientific Event Alert Network Bulletin, 13:4. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198804-332010.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
Activity . . . continued at a low level during the first 24 days of April. The level of the lava pond on the newly named Kupaianaha shield remained 20-25 m below the rim. Lava entered the ocean along 3 or 4 fronts straddling Kupapau Point. A few minor surface flows occurred near the shoreline. Harmonic tremor generally continued at a low level . . . near Pu`u `O`o and Kupaianaha shield. Minor changes in tremor amplitude occurred at varying intervals ranging from a few minutes to many days. At the summit, the number of shallow microearthquakes persisted at a low level of ~100/day during the first three weeks of April, coinciding with summit deflation. Shallow and intermediate-depth tremor occurred sporadically in the summit region. Moderate-sized earthquakes of M 2-4 continued to be most frequent in the S of the island.
On 24 April the lava level in the pond began to drop and by the end of the day was 30 m below the rim. By the next morning lava was down another 5-10 m and there was little surface overturn activity. Large sections of the pond rim had become unstable and collapsed into the pond. The lava had drained to below the level of the outlet tube but did not retreat into the conduit. Slowly solidifying lava remained in the bottom of the pond with remnants of the pahoehoe skin that had covered the surface . . . . A few sluggish flows continued to enter the ocean from residual drainage of the tube system. One small aa outbreak occurred at the 450-m level, probably a result of tube collape. Three kilometers uprift, lava had been visible in the bottom of the Pu`u `O`o conduit on 24 April. On the 25th, heavy fume prevented observation, but no orange glow was evident over Pu`u `O`o at night during the decreased activity of the next several days. There was no seismic evidence indicating where blockage may have occurred in the feeder dike between the summit and the eruptive areas in the middle East rift zone. East-rift tremor decreased to a low and constant level between 25 and 28 April. Tremor remained relatively steady but gradually increased in amplitude from the 28th to the end of the month. Microearthquakes increased during the last week of the month from 100/day to a peak level of > 500/day as the summit re-inflated. This slight inflation at the summit during the hiatus in lava production did not exceed fluctuations often measured during previous months.
Shortly after 0500 on 1 May, after nearly a week of quiescence, lava re-entered Pu`u `O`o crater and the pond at Kupaianaha shield. Episodic tremor resumed . . . following the onset of summit deflation. At 1100 lava was observed streaming from the W side of Pu`u `O`o crater and draining into its central vent. The lava pond at Kupaianaha had refilled to ~8 m below the N rim. By 1400 lava was within 5-6 meters of the rim. On the morning of 2 May lava had re-entered the December-April tube system and broke out . . . at six places between the base of the shield and 470 m elevation. Only the four lowest breakouts were active late in the day. Lava also overflowed from the pond onto the NE sector of the shield and into the neck area. These flows were <150 m long. On 12 and 13 May, lava overran the two remaining inhabited houses near the E edge of the lava field.
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.