Tuesday, 29 November 2011

Volcanic and seismic awakening of Pan-America

The seismic and volcanic awakening of Pan-America is now well underway. The Caribbean Plate comprises an area of roughly 3.2 million square km (1.2 million square miles) and it is undergoing major stress. 
A series of seismic swarms in this region resulted in the outbreak of a 5.1magnitude earthquake which struck off the coast of San Juan Puerto Rico today. The northern boundary of the Caribbean Plate with the North American plate is a transform or strike-slip boundary which runs from the border area of Belize, Guatemala (Motagua Fault), and Honduras in Central America, eastward through the Cayman trough on south of the southeast coast of Cuba, and just north of Hispaniola, Puerto Rico, and the Virgin Islands. Part of the Puerto Rico Trench, the deepest part of the Atlantic Ocean (roughly 8,400 meters), also lies along this border. The Puerto Rico trench is at a complex transition from the subduction boundary to the south and the transform boundary to the west. The Cocos plate on the western border of Pan America is subducting under the Caribbean Plate. The whole region is becoming more violent as geological forces increase plate pressures on the region and the sea-floor is violently stirred along the Puerto Rico trench. The trench has an unsettling history of producing very powerful earthquakes- 8.1 magnitude earthquakes struck the region both in 1787 and 1946. In light of the rising earthquake risks, UNESCO conducted aCaribbean Tsunami  warning exercise on March 23, 2011 in anticipation of a 7.6 magnitude earthquake. It goes without saying, we’re overdue for another major earthquake to strike this region. As a result of the mounting seismic tension on the western region of the plate, we’re already witnessing the volcanic and seismic awakening of much of Pan-America. On November 20, Mexico’s Popocatepetl volcano unleashed a 5 km ash cloud. On November 22nd, Guatemala’s lofty Fuego volcano followed suit with a 2 km cloud of dark ash. On November 25th, the alert status of Colombia’s Gelaras volcano was raised to orange. On November 26th, the dense upper volcanic belt of El Salvador was shaken by a swarm of over 700 tremors in a 24-hour-period. Now Ecuador’s Tungurahua volcano is the latest telltale sign that the time-bomb in the Atlanic is still ticking.

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