HVO reported that lava at Kilauea's Halema`uma`u Crater lava lake circulated in a 20-m-diameter area on 19 May but was stagnant and crusted over on other days through 25 May. A few minor oozes of lava between the W vent and main island were occasionally visible. The depth of the lava lake was 229 m and had remained unchanged since 11 May. Sulfur dioxide emissions were 100-150 tons per day during 19-23 May, close to the less than 50 tonnes per day measured during the non-eruptive period from late 2018 to late 2020. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

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)