During 18-24 March, HVO reported that lava flowed SE from underneath Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex through a lava tube system, reaching the Waikupanaha and Kupapa'u ocean entries. Activity near the Prince Lobe was noted, and thermal anomalies seen on satellite imagery during most days suggested surface flows on the coastal plain. Explosions from the Waikupanaha ocean entry were seen on 19 March. During 19-20 March, the Kupapa'u bench was 450 m wide (along shore) and extended 70 m into the ocean.

The vent in Halema'uma'u crater continued to produce a predominantly white plume, occasionally tinged brown, that drifted mainly SW. Incandescence was intermittently seen from the vent, and sounds resembling rushing gas were sometimes heard in the vicinity of the crater. Tephra and some glassy spatter were retrieved almost daily from collection bins placed near the plume. On 20 March, geologists utilizing an infrared camera saw that a single small spattering vent (another was out of sight to the E) at the bottom of a large overhung cavity beneath the Halema'uma'u crater floor emitted gas and steam. The sulfur dioxide emission rate at the summit was 500 and 900 tonnes per day on 19 and 23 March, respectively; the 2003-2007 average rate was 140 tonnes per day.

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)