Friday 31 August 2012

Large Earthquake near Jan Mayen Island.

On Thursday 30 August, slightly before 1.45 pm local time (which is the same as GMT), the United States Geological Survey recorded an Earthquake measuring 6.8 on the Richter Scale at a depth of 9.9 km, on the Mid-Atlantic Ridge, roughly 400 km east of Greenland. This is a large Earthquake and could cause considerable problems in an inhabited area, though it is unlikely to have done so in the remote North Atlantic, where the only inhabited place likely to have felt shaking would be Jan Mayen Island, 100 km southeast of the quake's center, where the Norwegian Armed Forces and the Norwegian Meteorological Institute both maintain bases, the island's population occasionally rising as high as 35. This quake was followed after about eight minutes by another quake roughly 5 km southeast of Jan Mayen, this time measuring 5.2 on the Richter Scale, at a depth of 12.3 km.

Map showing the locations of the first (A) and second (B) quakes on 30 August 2012. Google Maps.

The Mid-Atlantic Ridge is a divergent plate margin running the length of the Atlantic from north to south, and separating North and South America to the west from Eurasia and Africa to the east. The Atlantic is spreading at an average rate of 25 mm per year, with new seafloor being produced along the rift volcanically, i.e. by basaltic magma erupting from below. In places this produces volcanic activity above the waves, in the Azores, on Iceland and on Jan Mayen Island itself, where the Beerenberg Volcano is the most northerly active volcano on the planet.

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