The western Atlantic Ocean island of Bermuda, which was hit by its first earthquake in over a decade in April, has been rattled by two moderate quakes.

The earthquakes, both measuring 4.5 magnitude on the Richter Scale, struck at 10:18 PM and 10:36 PM local time on Monday.

Image
© Google EarthEpicentre of Monday night's earthquakes
The subsea quakes, the strongest to be recorded in the region in more than 20 years, were centred about 80 miles (130 km) south of Hamilton, the capital of the British overseas territory.

According to the United States Geological Survey (USGS), the quakes (1st, 2nd) occurred at depths ranging between 10 and 14 kilometres.

Geology of Bermuda

Seen from above the ocean's surface, the general characteristic or the islands is that of ridges, running from the North East to the South West, before turning towards the North. Together with the submerged, encircling reef, they form the edge of a volcanic caldera, to the south of which the islands lie. The islands enclose a smaller caldera, which forms the Great Sound, and another forms Harrington Sound. The volcano was formed on the fault line from which the Atlantic oceanic tectonic plates expand, pushing the Old and New Worlds away from each other. It has been theorised that the volcanoes were formed by the Bermuda hotspot, if that existed. A submarine volcanic mountain range, the Mid-Atlantic Ridge was formed atop this fault. Bermuda now sits far to the west of the ridge in foothills that once were the ridge.

Image
© USGSOnly 5 other earthquakes have been recorded near Bermuda since 1990. All other quakes were less than 4.5 magnitude.
This is because it is far older than other islands formed on the ridge, which lie much closer to the ridge (including Iceland, The Azores, Ascension Island, etc.). There are also two seamounts to the South-West of Bermuda, forming Argus Banks, and Challenger Banks.