During 23-30 September HVO reported that the circulating lava lake occasionally rose and fell in the deep pit within Kilauea's Halema'uma'u Crater. Gas emissions remained elevated. The plume from the vent continued to deposit variable amounts of ash, spatter, and Pele's hair onto nearby areas; smaller particles may have been dropped several kilometers away. Small collapses from the inner wall occasionally occurred and on 24 September produced a small brown plume from the vent. At Pu'u 'O'o Crater, glow emanated from several outgassing openings in the crater floor. Volcanologists on an overflight on 26 September observed sloshing lava in the pits.

The 27 June NE-trending lava flow remained active upslope from the leading edge. By 22 September the flow had extended 16.4 km from the vent (measured in a straight line), placing the active flow front within the NW portion of the Kaohe Homesteads, a vacant forested portion of the subdivision, 2.3 km upslope from Apa`a Street and 3.3 km from Pahoa Village Road. Two slow-moving lobes behind the flow front advanced; the nearest lobe was about 125 m behind the stalled front. During an overflight on 29 September volcanologists observed breakouts where the flow first entered the crack system about 8 km behind the stalled front, and where it exited the system about 3 km upslope from the front. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Warning.

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.

Source: US Geological Survey Hawaiian Volcano Observatory (HVO)