The lava production . . . at Kīlauea's new shield vent has continued at about the same rate as the previous four months. The height of the new pahoehoe shield remained at ~46 m, while lava spillovers have increased its diameter to > 1.6 km. An active lava pond remained on top, producing overflows beyond the shield margins, mostly to the E and SE, during early November. The lava pond was ~200 x100 m, elongated toward the SE, with a narrow neck that roofed over to form the main tube of the complex flow system. The level of the lava pond fluctuated between periodic overflows to as much as 10 m below the rim. Magma output was estimated to be [500,000] m³/day.

Flows extended E, surrounding Kalalua (a prehistoric cinder cone), to Puʻu Kiai, formed by the September-October 1977 eruption and SE against the margin of the 1977 flows. By 20 November, a narrow flow had moved SSE to ~270 m elevation, advancing at 200-300 m/hour on the steeper slope. By a process of extending the tube network and widening, lava moved to ~60 m elevation late 23 November, threatening several houses at Kapa'ahu (figure 47). On 25 November at 2350, the 20-30-m-wide flow reached the coast highway. A second lobe of the flow was further W, near the April 1984 flow, and a third lobe later bypassed a popular fresh water natural pool (Queens Bath) used for swimming. The lava flowed W along the highway, slowing and spreading laterally for a few hours, then crossed it and destroyed nine houses the next morning. Several more were threatened. All residents of the community had been evacuated. Lava moved slowly over the gradual slope S of the highway and entered the ocean, 12 km from the vent, on 28 November (figure 47). By the next day, lava had covered ~200 m of shoreline and extended 30 m into the sea. Several small lobes broke away from the main flow on 30 November, threatening four more houses.

On 3 December most of the lava produced at the vent was entering the ocean, but in the next 2 days decreasing amounts of lava reached the ocean because of blockages within the tube system. The lava pond was filled and overflowing on 5-6 December, then blockage cleared or was bypassed by lava breaking out and overriding earlier flows. New lobes consumed two more houses on 7-8 December. Pond spillovers caused short flows to the NE and SE. A total exceeding 0.08 km² of new land had been added to the island as of 19 December.

Low-level harmonic tremor persisted near the eruptive area . . . . Microearthquakes in the summit region continued to gradually increase. At mid-month a moderate burst of intermediate-depth low-frequency (long-period) earthquakes occurred ~5-15 km below the summit. More than 700 events of M 0.1-2.0 were associated with harmonic tremor and magma movement. Activity peaked 17-20 November, then declined.

Summit tilt, measured by EDM instruments and other tiltmeters around the caldera, was unchanged. Electronic tiltmeters were affected by heavy rains throughout the month and no new data were available.

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: C. Heliker and R. Koyanagi, HVO.