Report on Kilauea (United States) — October 1977
Natural Science Event Bulletin, vol. 2, no. 10 (October 1977)
Managing Editor: David Squires.
Kilauea (United States) Eruption near the Kalalua cone ends on 1 October
Please cite this report as:
Global Volcanism Program, 1977. Report on Kilauea (United States) (Squires, D., ed.). Natural Science Event Bulletin, 2:10. Smithsonian Institution.
19.421°N, 155.287°W; summit elev. 1222 m
All times are local (unless otherwise noted)
The following is from Gordon Eaton. "At approximately 1930 on 13 September an eruption broke out on the central E rift, near Kalalua, a prehistoric cinder cone (see table 2 for detailed chronology). It followed a swarm of earthquakes that began on the previous day at 2130 on the upper E rift, near the young satellite shield, Mauna Ulu, and Makaopuhi crater. These earthquakes were accompanied by harmonic tremor and rapid summit deflation, indicating that magma was moving into the E rift in the subsurface. The deflation continued strongly for about a week and then tapered off gradually. A total of 90 µrad of tilt change was measured on the tiltmeters at Uwekahuna vault. Levelling later showed maximum summit subsidence of 44 cm."
|12 Sep 1977||2130||Earthquake swarm began in the upper E rift.|
|12 Sep 1977||2200||Summit deflation began.|
|13 Sep 1977||mid-morning||Earthquake hypocenters began to migrate E along the E rift.|
|13 Sep 1977||1930||Fountaining began at newly opened fissures extending 3 km E from Kalalua Crater, accompanied by heavy harmonic tremor. Total summit deflation (as measured at Uwekahuna) had reached about 42 µrad.|
|14 Sep 1977||0800||Fountaining was confined to the E one-third of the new fissures, feeding a lava flow moving S. Summit deflation, 3.5 µrad/hour.|
|15 Sep 1977||0200||Two areas of fountains, about 60 m high. Activity along remainder of the fissure was confined to low spattering. The deflation rate had declined to about 1 µrad/hour; total subsidence was about 75 µrad.|
|15 Sep 1977||late afternoon||First phase of the eruption ended, after the lava flow had advanced about 2.5 km. Earthquakes and harmonic tremor had declined. Total summit deflation was about 85 µrad.|
|15 Sep 1977||2400||Harmonic tremor ended.|
|16 Sep 1977||0400||Renewed fountaining (phase 2), feeding a small flow [but see 02:10] parallel to the first flow. Fountains were discontinuous, rising to about 50 m from a vent area about 200 m long, slightly W of the earlier vents.|
|18 Sep 1977||1530||The eruption had declined to weak, intermittent spattering, and the new flow had stopped less than 0.5 km from the vent. Harmonic tremor was still being recorded from the vent area, but not from the summit, where deflation had ended. Earthquakes had declined.|
|20 Sep 1977||evening||Phase 2 activity ended [but see 02:10].|
|23 Sep 1977||early afternoon||Minor fountaining (to 15 m) fed small flows, and ended by nightfall (Phase 3).|
|25 Sep 1977||2350||Phase 4 began from a vent W of the earlier ones. During the next 24 hours, fountains rose 100 m, and discharge rates briefly reached an estimated 5-7 x 105 m3/hour. Lava advanced SE at up to 300 m/hour.|
|29 Sep 1977||--||Kalapana, a coastal village with population about 250, [but see 02:10] was evacuated. The flow front, several thousand meters from the village, was advancing toward it about 150 m/hour down a steep slope. A transition from pahoehoe to aa flow types occurred at the edge of the steep slope.|
|30 Sep 1977||0300||The fountains feeding the flow declined to 20-30 m and the flow had slowed to 60-90 m/hour after reaching a gentler slope. Summit tilt remained irregular, varying 2 µrad throughout phase 4.|
|01 Oct 1977||1000||Flow advance had stopped 400 m from the nearest house in Kalapana. The pahoehoe to aa transition had retreated to the vent area. The flow front had thickened from 4.5 to 12 m and had widened from 300 to 900 m.|
|01 Oct 1977||1530||Harmonic tremor near the vent declined markedly.|
|01 Oct 1977||1625||Fountaining stopped, after building an irregular 100 m [but see 02:10] spatter cone.|
"The initial active section of rift was approximately 5.5 km long, but fountaining at all times and locations was restricted to a few hundred meters of this length. The remainder of the rifted zone opened as a series of en echelon fractures and were sites of profuse steaming. Maximum fountain heights reached during the early phases of the eruption did not exceed 70-80 m. Flows at that time consisted chiefly of aa, with a maximum rate of advance of about 170 m/hour. By dawn on 15 September these flows had slowed to 65 m/hour. They came to rest about 2.5 km from their source fountains, close to a papaya field and ranch.
"On 18 September new fountaining began uprift, immediately NW of Kalalua cone, several kilometers from the initial fountains. By late afternoon on 19 September this activity had decayed and flow movement was scarcely perceptible, but by midnight fountaining resumed. By 0900 hours on 20 September this phase of the eruption had ended.
"The next phase consisted of Strombolian activity at a small, new cone downrift in the afternoon of 23 September. The lava was highly viscous and was ejected sporadically in a series of taffy-like, irregular sheets and long clots. All lava to this point in the eruption was tholeiite rich in plagioclase microphenocrysts, presumably old and highly differentiated lava.
"The period 24-25 September was free of activity at the rift. Harmonic tremor decayed to very low levels. Just before midnight on 25 September, however, tremor resumed and strong glow was visible over the rift. Heat from the eruption domed a blanket of stratus clouds over the volcano into a huge cumulus cloud. Harmonic tremor amplitude rose at the two seismometers closest to the fountaining. Except for a 2-hour lull in the early afternoon of 26 September this fountaining continued until mid-afternoon on 1 October. Fountains played from heights of 20 m to as much as 300 m, lava production was copious at all times, and the new flows ran NE, ENE, and SE, but only the ENE flow eventually threatened populated areas. In the early hours of 28 September it turned away from the rift down which it had flowed for 1.5 km and started toward the village of Kalapana. Evacuation of Kalapana began at dawn 30 September and was completed by evening.
"On 1 October at 1530 tremor levels along the central E rift dropped dramatically. Fountaining had ceased by 1615. It did not resume again, although measurable tremor continued through 12 October.
"Evacuees returned 3 October, 38 hours after cessation of fountaining. The source cone, named Pu'u Kia'i (Hill of the Guardian) is 250 m long, 140 m wide, and 35 m high."
Further Reference. Moore, R.B., Helz, R.T., et al., 1980, The 1977 Eruption of Kilauea Volcano, Hawaii; JVGR, v. 7, p. 189-210.
Geological Summary. 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: G. Eaton, HVO.