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Japan:Meteorological agency to revise tsunami alerts

Wednesday, July 27, 2011

Laaska News  July 27,2011

Japan’s Meteorological Agency says it will develop a new plan for issuing tsunami alerts in the aftermath of major earthquakes. The maximum possible alerts will be given, and then downscaled accordingly after the actual magnitude of the earthquake has been determined.

On March 11th, the agency initially estimated the magnitude of the massive earthquake as 7.9. It used this information to issue warnings for tsunami of 6 meters in Miyagi Prefecture and 3 meters in Iwate and Fukushima prefectures. The predictions were then gradually raised to more than 10 meters after the agency confirmed the actual height of tsunami waves offshore.

But due to power outages, the revised figures were not thoroughly conveyed. Many people never knew that the expected height of the tsunami had been raised.
On Wednesday, the agency announced that it will seek to avoid such misinformation by changing the way it issues tsunami alerts. It said it will seek to ensure that the new alerts are issued just as quickly as in the current system.

The agency said that when an earthquake with a magnitude of 8 or higher strikes, it will first issue the maximum possible alerts. This is due to the possibility of underestimating the size of earthquakes and tsunami in the aftermath of such powerful quakes.

After the initial alerts are issued, the agency will downscale them as the magnitude of the quake is more accurately determined.

Agency officials did not say whether they would also provide the expected height of tsunami in the initial alert.

The meteorological agency plans to finalize a report on the new alert by the end of the year.

NHK.

 

 

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