During 22-28 December, several areas of surface lava were visible at Kilauea along the PKK lava flow on the coastal flat, and along the Pulama pali fault scarp. Overall seismicity at the summit was low, but a few long-period earthquakes continued to occur. Tremor was essentially absent at the summit and moderate at Pu`u `O`o cone. On 26 December, surface ground motion from a deadly M 9 earthquake just W of Sumatra was picked up by all tiltmeters at Kilauea. During the report period, small periods of inflation and deflation occurred at the volcano.

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)