During 26 May-1 June HVO reported that activity at Kilauea continued from the summit and the east rift zone. At the summit, the level of the circulating, crusting, and bubbling lava-pool surface remained mostly stable in the deep pit inset within the floor of Halema'uma'u crater; glow from the vent was visible. On 31 May the surface rose to the highest level yet recorded, but was still more than 100 m below the Halema'uma'u crater floor.

At the east rift zone, lava flows that broke out of the TEB lava-tube system had advanced down the Pulama pali onto the coastal plain and headed S, entering the ocean at Ki. Other lava flows were active above the pali. On 27 May geologists noted a small rootless shield building up at a break-out point at 580 m elevation. Small lava flows issued from vents on Pu'u 'O'o's S crater wall during 26-27 May, and pooled on the crater floor at least through 31 May.

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)