Thursday 29 March 2012

Volcanic activity on Soufrière Hills, Montserrat.

Soufrière Hills is an active stratovolcano (singular, 'Hills' is part of the name; a single cone-shaped volcano with several summits) in the south of the island of Montserrat, in the Leeward Islands. The summit of the volcano rises 915 m above sea-level, and it has a 1 km wide crater, breached to the east by an eruption about 4000 years ago which caused a summit collapse.

On 22 Thursday March 2012 Soufrière Hills was struck by a swarms of Earthquakes between 4.00 and 5.00 pm. This was followed by a second, larger, Earthquake swarm between 3.00 and 5.30 on Friday 23 March. Later that day a new fumerole (gas emitting vent) was spotted on the northwest part of the volcano, and an ash plume rose 1.8 km above the volcano.

This is the first significant eruptive activity on Soufrière Hills in 2012, but is still considered to be part of the volcanic cycle which began in 1995, and which has caused a great deal of disruption on Montserrat, destroying the capitol, Plymouth, and causing the southern half of the island to be evacuated (mostly overseas).

The remains of Plymouth. June 2004. Montserrat Volcano Observatory.

Prior this there had been occasional (but rare) outbreaks of Earthquake activity on Soufrière Hills, but no significant eruption since about 1630.

The Leeward Islands are located at the eastern fringe of the Caribean Tectonic Plate. The Atlantic Plate is being subducted beneath this, and as it sinks into the Earth, is melted by the heat of the planets interior. Some of the melted material then rises up through the overlying Caribbean Plate as magma, fueling the volcanoes of the Leeward Islands and Windward Islands (together the Lesser Antilles Volcanic Arc).

The subduction of the Atlantic Plate beneath the Caribbean Plate fuels the volcanos of the Lesser Antilles Volcanic Arc. George Pararas-Carayannis.