5.9 magnitude quake no risk to island

Earthquake in Tristan da Cunha Region

Mid-Atlantic Ridge Earthquake 215 miles from Tristan

A 5.9 magnitude earthquake occurred on Monday 31st August 346km WNW of Tristan da Cunha at a depth of 10km. This earthquake is typical of many regular events along the Mid-Atlantic Ridge which lies some 350 km west of Tristan da Cunha. The ridge is the centre of sea-floor spreading as shallow magma convection currents push upwards and force the South American and African tectonic plates apart. The quakes are often accompanied by the eruption of basalt lava on the ocean floor, usually billowing out to form rounded shapes called 'pillow' lava, as they resemble cushions. Earthquakes of this magnitude are seldom felt on Tristan da Cunha, and are of no significance to the island community.

Tristan da Cunha itself is an active hot-spot volcano, fed by deep magma currents. Since the October 1961 eruption, which led to the evacuation of the entire Tristan population to the UK, there has been one submarine volcanic eruption in 2004, but no further significant seismic activity recorded. The island community is alert for any further locally centred earthquakes which may be the prelude to a future volcanic eruption. The Tristan Government has a Disaster Management Plan and holds periodic drills to revise procedures in the event of a volcanic emergency.