WEBVTT
Kind: captions
Language: en

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These are the sounds of a tsunami warning.

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They alert residents that a killer wave is
about to strike.

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These sirens, however, are just a small part of the sophisticated warning systems that

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played a role in Japan and in the U.S. during the Pacific Ocean

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tsunami in March 2011.

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Most Tsunamis are generated by an undersea earthquake.

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Fortunately, Japan has one of the most
advanced earthquake early-warning systems

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in the world.

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It detects tremors, calculates the epicenter, and sends out warnings from over a thousand

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seismographs scattered throughout the country.

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The Japan Meteorological Agency issues the warnings and sends alerts to television and

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radio channels,
the internet, and mobile phone networks.

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When the earthquake struck 80 miles offshore, warnings were

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generated in about three seconds.

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The tsunami warnings came three minutes later.

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These take longer because more complex calculations are involved, and must factor in ocean data.

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Since the first tsunami waves struck the coastline within 20

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minutes, the advance warning provided some residents with crucial minutes to reach a safe area.

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While the earthquake sent powerful tsunami waves westward toward Japan, the tsunami also

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propagated
east into the Pacific Ocean.

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Here, warnings are issued by the Pacific Tsunami Warning Center, operated by NOAA in Hawaii.

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NOAA maintains a large network of buoys with ocean floor sensors that are strategically

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positioned in the earthquake-prone zones of the Pacific.

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This system collects vital ocean data for
tsunami forecasting.

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On March 11th, only 25 minutes after the earthquake

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struck, the first buoy station registered
the tsunami

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and relayed information to Hawaii.

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Scientists used this data to run models and issue forecasts and

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warnings to nations throughout the
Pacific.

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From there, local emergency managers decided what actions

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were appropriate to take for public
safety.

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The earthquake and resulting tsunami devastated the Japanese coastline, causing damage that

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will take years to repair.

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While we can’t prevent these forces of nature from happening, our early warning systems

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can help us prepare for the dangers headed our way.