Sunday, February 28, 2010
WASHINGTON: A tsunami triggered by the powerful quake that rocked Chile was Saturday racing across the Pacific Ocean towards Hawaii and Asia at around 450 miles per hour, a quake expert said.
Estimating the depth of the wave's water column to be around four kilometers (2.4 miles) on average, Roger Bilham, a professor of geological sciences at the University of Colorado, calculated that at mid-ocean, the mass of water would be hurtling toward Hawaii at 200 meters per second, or 720 kilometers per hour (446 mph).
"Mid-ocean, the wave is travelling at around the speed of a jet plane," Bilham told media. "The amplitude of the wave is small when it's mid-ocean, but it may rise to five to 10 meters when it reaches Japan or the Philippines," he said.
A huge arc of nations around the Pacific, from New Zealand to Japan, have gone on tsunami alert, while sirens sounded warnings of destructive waves around Hawaii for the first time in 16 years.
The powerful 8.8-magnitude quake that rattled Chile in the early hours of Saturday occurred offshore in a subduction zone -- the point where two tectonic plates meet and one plunges beneath the other.
The undersea earthquake that set off the 2004 Asian tsunami, which killed nearly 200,000 people and left hundreds of thousands homeless, was also a subduction earthquake.
"Subduction zone earthquakes produce the world largest tsunamis because the sea floor moves like a piston, heaving 100 kilometer by 50 kilometer (60 miles x 30 miles) or larger regions of sea floor water up or down," Bilham told media.
The US Geological Survey said the first tsunami wave was expected to hit Hawaii at around 11:19 am local time (2119 GMT).
"The danger can continue for many hours after the initial wave as subsequent waves arrive," the USGS warned. "Tsunami wave heights cannot be predicted and the first wave may not be the largest."
Bilham expected the huge waves will smash ashore in Japan seven hours after hitting Hawaii.
WASHINGTON: A tsunami triggered by the powerful quake that rocked Chile was Saturday racing across the Pacific Ocean towards Hawaii and Asia at around 450 miles per hour, a quake expert said.
Estimating the depth of the wave's water column to be around four kilometers (2.4 miles) on average, Roger Bilham, a professor of geological sciences at the University of Colorado, calculated that at mid-ocean, the mass of water would be hurtling toward Hawaii at 200 meters per second, or 720 kilometers per hour (446 mph).
"Mid-ocean, the wave is travelling at around the speed of a jet plane," Bilham told media. "The amplitude of the wave is small when it's mid-ocean, but it may rise to five to 10 meters when it reaches Japan or the Philippines," he said.
A huge arc of nations around the Pacific, from New Zealand to Japan, have gone on tsunami alert, while sirens sounded warnings of destructive waves around Hawaii for the first time in 16 years.
The powerful 8.8-magnitude quake that rattled Chile in the early hours of Saturday occurred offshore in a subduction zone -- the point where two tectonic plates meet and one plunges beneath the other.
The undersea earthquake that set off the 2004 Asian tsunami, which killed nearly 200,000 people and left hundreds of thousands homeless, was also a subduction earthquake.
"Subduction zone earthquakes produce the world largest tsunamis because the sea floor moves like a piston, heaving 100 kilometer by 50 kilometer (60 miles x 30 miles) or larger regions of sea floor water up or down," Bilham told media.
The US Geological Survey said the first tsunami wave was expected to hit Hawaii at around 11:19 am local time (2119 GMT).
"The danger can continue for many hours after the initial wave as subsequent waves arrive," the USGS warned. "Tsunami wave heights cannot be predicted and the first wave may not be the largest."
Bilham expected the huge waves will smash ashore in Japan seven hours after hitting Hawaii.
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