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'Ring of Fire' shakes Peru
16/08/2007 22:31 - (SA)
Lima - Peru has become the latest country to be shaken by the "Ring of Fire," a 40 000km arc of seismic violence that unleashes earthquakes and volcanoes around the Pacific rim almost every day.
Hundreds of people were killed and more than a thousand injured, Peruvian authorities said, after the 7.9-magnitude quake rattled the country on Wednesday afternoon.
Several cities were devastated and aftershocks measured up to 6.3, according to the US Geological Survey.
The Ring of Fire, as geologists call it, stretches along the western coast of the Americas, across the densely populated island nations of East and Southeast Asia, and through the South Pacific.
Pressure causes crust to buckle and shift'
"Most of the seismic energy released on the Earth is somewhere along the Pacific margin," explained Roger Musson, a seismologist at the British Geological Survey.
All but one of the last century's largest temblors have occurred somewhere along its path, where great chunks of the earth's crust - floating on the molten rock of the Earth's core -pull apart or butt up against each other competing for space.
This accumulating tectonic pressure is released through volcanic eruptions when the molten rock is ejected as magma through fissures in the crust, and via earthquakes when the pressure causes the crust to buckle and shift.
Most of these seismic events are small or occur under the sea, causing little or no loss of life or damage to property.
But occasionally they generate massive volcanic explosions, earthquakes or landslides.
A monster quake off the coast of Sumatra in 2004 - along with the Tsunami is set in motion - killed more than 280 000 people in a half-a-dozen nations.
While experts agree that the Ring of Fire generates more than 80% of the world's earthquakes, they differ as to how far their impact can travel.
"The earthquake that just happened in Peru is undoubtedly related to an 8.4-magnitude earthquake six years ago," said Musson.
A large section of the boundary between the tectonic plates that run along the Peruvian coast - the Nazca under the Pacific and the South American Plate - ruptured, creating pressure further down the fault, he explained.
"Where the earthquake in 2001 left off is where this one started," he said, adding that seismologists predicted at the time that another tremble would follow within decades. "It just happened a bit sooner than we expected."
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