Manam Motu erupts twice in August.

Manam Motu, a volcanic island off the north coast of Papua New Guinea, erupted twice in August 2020, producing a 2.1 km high ash column on Thursday 20 August and a 4.6 km high ash column on Monday 31 August. Both drifted to the west, and prompted the Darwin Volcanic Ash Advisory Centre to issue warnings to aviation.These are the first recorded eruptions on the island since May this year.

 

The extent of the ash cloud produced by Manam Motu on 31 August 2020. Volcano is located on an island of the north coast of Papua New Guinea, which is the landmass in the southwest part of this map. Darwin Volcanic Ash Advisory Centre.

Manam Moto is essentially a submarine stratovolcano (cone-shaped volcano) with its tip sticking above the sea, forming a 10 km diameter circular island with the summit of the volcano at the centre. The island is remarkably symmetrical, with four valleys at 90° angles leading from the summit to the sea, which carry ejecta from the frequent eruptions.

 

The location of Manam Moto. Google Maps.

Manam Motu is located on the southern margin of the South Bismarck Plate, close to its boundary with the Australian Plate, which underlies the Papuan mainland. The Australian Plate is being subducted beneath the South Bismarck, and as it does so it is partially melted by the friction and the heat of the planet's interior. Some of the melted material then rises up through the overlying South Bismarck Plate as magma, fuelling the volcanoes of the north Papuan margin.

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