During 14-20 April activity reported by HVO at Kilauea was continuing at the summit and the east rift zone. At the summit, episodic rising and falling of the lava column continued at the deep pit inset within the floor of Halema`uma`u crater. Cycles occurred every 10-20 minutes until becoming more sporadic the evening of 14 April. On 15-16 April there were only 1-2 cycles/day. Activity increased again on the 17th, with cycles every 10-30 minutes. Glow from the vent was visible when the rising and falling cycles were frequent. On most mornings the plume of gas and ash from the summit vent drifted SW, depositing small amounts of tephra near the vent. Sulfur dioxide emission rates measured at the summit on 12, 14, 15, and 19 April were in the 600-790 tonnes/day range.

At the east rift zone, lava flowed through tubes to supply surface flows that advanced down the Pulama pali towards the coastal plain; on 16 April those flows were within 300 m of the coastal plain. Sulfur dioxide emission rates from the summit and east rift zone vents remained elevated. Geologists in the field on 17 April reported that the flow front had reached the E margin of the older Thanksgiving Eve Breakout (TEB) flow field on the coastal plain. On 19 April the flow front headed SE along the east margin of the TEB flow field, just W of the end of the Kalapana access road, and was 380 m NW of the viewing area.

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)