During 16-22 May HVO reported that the circulating and spattering lava lake periodically rose and fell in the deep pit within Kilauea's Halema'uma'u Crater, and spilled over the deep inner ledge on multiple occasions. On 15 May laser measurements indicated that the lava-lake surface was about 65 m below the Halema'uma'u Crater floor, among the highest levels measured; the lake rose five more meters during 18-19 May. Almost daily measurements indicated that the gas plume from the vent continued to deposit variable amounts of ash, and occasionally fresh spatter from the margins of the lava lake, onto nearby areas. A lava pond in a small pit on the E edge of Pu'u 'O'o crater floor remained active with spattering. On 19 May a small collapse of the N rim of the pit slightly enlarged the pit and lava pond within. A small lava flow erupted from a vent on the S part of the floor. Lava flows were active on the pali and the coastal plain, and were about 750 m from the sea.

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)