(Describer) Under a round logo of a wave, title: Ocean Today.

[dramatic music playing]

(Describer) The red and white flag of Japan fills the screen, then slides away to reveal Japan's islands. Titles: Tsunami Strike - Japan. Part 2: Propagation.

(male narrator) Eighty miles east of Japan, a 9.0 magnitude earthquake rocks the ocean floor.

(Describer) In computer animation, part of the floor breaks and rises.

[creaking]

This disturbance causes a transfer of energy from the seafloor to the ocean, generating a series of ocean waves known as a tsunami.

(Describer) A long swell moves and gets bigger.

In about 20 minutes, waves strike the Japanese coastline. Other nations go on high alert because the tsunami was propagate, or spread, throughout the Pacific Ocean.

(Describer) Computer-enhanced satellite images show the entire Pacific Ocean.

As the tsunami radiates outward from Japan, it encounters a variety of ocean features, such as ridges and underwater volcanoes, which guide the tsunami and create a complex pattern of scattering and reflective waves. In eight hours, the waves reach the Hawaiian islands, and in nine and a half hours, the West Coast of the United States. In 16 hours, the tsunami reaches the Indian Ocean and New Zealand, and by 22 hours, the entire Pacific Ocean had been affected. The impact of a tsunami can be highly variable because of the complicated interactions with ocean features and coastline elements. Wave height and speed will differ from place to place. Since tsunamis can be hundreds of miles long, and travel thousands of miles from where they originated, they are considered a worldwide threat when they form.

(Describer) Logos are shown for the Smithsonian and NOAA. Accessibility provided by the US Department of Education.

Accessibility provided by the U.S. Department of Education.