HVO reported that the eruption at Kilauea’s Lower East Rift Zone (LERZ) and within Halema`uma`u Crater continued during 11-17 July. Lava fountaining and spatter was concentrated at Fissure 8, feeding lava flows that spread through Leilani Estates and Lanipuna Gardens subdivisions, and built out the coastline at multiple ocean entries.

Inward slumping of the crater rim and walls of Halema`uma`u continued, adjusting from the withdrawal of magma and subsidence of the summit area. Explosions from collapse events occurred almost daily, producing gas-and-ash-poor plumes. Sulfur dioxide emissions from the summit were very low.

Fountaining at Fissure 8 continued, producing Pele's hair and other volcanic glass that fell within Leilani Estates. The fountains continued to feed the lava flow that traveled NE, and then SSE, W of Kapoho Crater. A few channel overflows occurred. The channelized ‘a’a flow reached the ocean on 12 July, producing a large plume of laze (a corrosive steam plume mixed with hydrochloric acid and fine volcanic glass particles), and covering the Kua O Ka La Charter School and Ahalanui Beach Park. Lava entered the ocean at several points along a broad 6-km-wide flow front, though the main entry area was at Ahalanui (750 m NE of Isaac Hale Park) by 17 July. On 13 July a new island, 6-9 m in diameter, formed a few meters offshore, possibly fed by a submarine tumulus. On 16 July explosions were noted at the main ocean entry, some were strong. Hawaii County Civil Defense Agency noted that an explosion early in the morning ejected tephra that injured 23 people on a nearby tour boat. That same day volcanologists using a radar gun measured an average flow velocity of 29 km/hour of lava exiting Fissure 8.

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.

Sources: US Geological Survey Hawaiian Volcano Observatory (HVO), Hawaii County Civil Defense Agency