Warning tsunami causes, but not Quake damage

Two weeks before a scheduled around in the basin of the Pacific, an earthquake of magnitude 7.9 yesterday to Tonga Islands tsunami early warning system test provided a more urgent test, unscheduled, briefly, causing fears of New Zealand tsunami to Hawaii.

Skip to next paragraph a magnitude 7.9 earthquake was briefly raised Tonga tsunami fears. A series of four hours television and interactive web site for The Times, The Canadian Broadcasting Corporation and Germany.nytimes.com/chinarises ? network ZDF

Indicators of tides recorded a tsunami as result of the earthquake, but the height of the peak to depression was only about 17 inches, not large enough to cause damage. No deaths were reported by the earthquake.

The earthquake occurred around 100 miles northeast of Nuku'alofa, travel agencies, one of the islands of Tonga, at 4: 26 am, local time. The geological service of United States initially estimated magnitude 8.0, large enough to be considered as "large", but only to the extent which could generate a tsunami dangerous threshold.

The National Oceanic and Atmospheric Administration in Hawaii Pacific Tsunami Prevention Centre issued a warning 17 minutes after the earthquake in the Pacific coastal areas. An hour later, the Centre downgraded the warning for only an hour afterwards and region within 600 miles from the epicenter, cancelled the alert.

Earthquake occurred along the border where the India-australiano tectonic plate meets the Pacific plate. It was near of 34 miles below the surface and not much deform the ocean floor. The deformation of the ocean bottom, moving large amounts of water, is the direct cause of tsunamis.

"This really was the perfect event," said Gerard Fryer, a geophysicist at the Centre of tsunami warning. "It was in an area that was populated, and there was a tide of 300 miles from where we could see it, and we could leave a warning in time."

He added that, "Fortunately, isn't necessary."

There are still problems in the system. Tonga, for example, did not receive the warning, due to a power failure.

On May 16, as part of a drill organized by Unesco, warning center starts the exercise using a mock tsunami alert. This would allow authorities in different countries to measure how long it takes to disperse the warning to emergency personnel.

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