Tuesday 22 December 2020

Eruption on Mount Kilauea, Hawai'i.

The Hawai'ian Volcano Observatory recorded a sharp rise in seismic activity beneath Mount Kilauea, on Big Island, at about 8.30 pm local time on Sunday 20 December 2020 (about 6.30 am on Monday 21 December GMT). This was followed about an hour later by the onset of eruptive activity in the volcano's Halemaʻumaʻu Crater, with incandescence (glowing) seen within the crater, followed by the rapid boiling away of a lake within the crater, producing a column of steam about 9 km high. The seismic activity continued throughout the night, with a Magnitude 4.4 Earthquake recorded below the volcano at about 10.30 pm. Once the water lake in Halemaʻumaʻu Crater had evaporated, lava was seen fountaining to about 25 m and the crater began to fill with a lava lake.

Steam plume over Mount Kilauea, Hawai'i, on 20 December 2020. Hawai'ian Volcano Observatory/USGS.

Investigations the following day (21 December 2020), showed that three new fissure vents had opened on the side of the Halemaʻumaʻu Crater, with lava pouring from these into the lava lake. Several local communities have reported ash falls, and the Hawai'ian Volcano Observatory is warning people close to the volcano to stay indoors due to concerns about toxic gasses being produced by the eruption, despite which the ongoing activity is reported to have attracted considerable crowds of onlookers in several places.

Aerial view of the Kīlauea summit eruption from a Hawaiian Volcano Observatory overflight at approximately 11.20 am, local time. The two active fissure locations continue to feed lava into the growing lava lake in Halema‘uma‘u crater, with the northern fissure (pictured right) remaining dominant. Hawai'ian Volcano Observatory/USGS.

 The islands of Hawai'i have formed as a result of hotspot volcanism, with a mantle plume hotspot currently located under Big Island, Hawai'i, and each of the other islands being the result of previous activity from the same hotspot, with the oldest Islands in the northwest and newest in the southeast. A volcanic hotspot is an area where magma from deep inside the Earth is welling up through the overlying plate (in this case the Pacific) to create volcanism at the surface. Volcanoes move as they erupt, swelling as magma enters their chambers from bellow, then shrinking as that magma is vented as lava.

The position of the Hawai'i Hotspot relative to the islands of Hawai'i. Joel Robinson/USGS/Wikimedia Commons.

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