Tsunamis are water waves that are caused by sudden vertical movement of a large area of the sea floor during an undersea earthquake.

Tsunamis can really cause some extensive damage. These Tsunamis are unleashed by submarine earthquakes or explosive volcanic eruptions. Each wave can cross an ocean at 500-800 kilometers per hour. In the ocean their amplitude is so low that they pass ships undetected. Tsunamis funneled into shallow shores may tower over 67 meters(220 feet). In 1883, Tsunamis from erupting Krakatoa killed more than 36,000 Indonesians. Some 300 Tsunamis have been recorded during the last 2500 years-most originating in or near the Pacific Ocean.

What happens when a tsunami encounters land?

As a tsunamis approaches land, it begins to slow down and grow in height. Just like other water waves, tsunamis begin to lose energy as they rush onshore, part of the wave energy is reflected offshore, while the shoreward-propagating wave energy is dissipated through bottom friction and turbulence. Even with those losses, tsunamis still reach the coast with tremendous amounts of energy. Tsunamis have erosional potential, stripping beaches of sand that may have taken years to gather and ripping out trees from the ground and other coastal vegetation.

The Height of a tsunami in the Ocean.

The height of a tsunami in the ocean is typically about 1 foot, but the distance between wave crests can be very long, more than 60 miles. The speed of a tsunami decreases as water depth decreases. In the Mid-Pacific, where the water depth reaches 3 miles, tsunamis speeds can be more than 430 miles per hour.

Historically, no tsunamis have been generated on the East Coast. This is because of the low level of seismic activity and the lack of vertical fault displacement. A tsunami wasn't even recorded during the Charleston, South Carolina earthquake of 1886, one of the largest earthquakes in the United States. The only tsunami to be recorded on the Atlantic Coast of the United States was generated by an earthquake off the Burin Peninsula of Newfoundland on November 18,1929. It caused a wave of 1 foot.

The West Coast is definitely the most common place for tsunamis to strike in the United States. The 1946 Aleutian tsunami produced waves at heights of 12 to 20 feet at Half Moon Bay, Muir Beach, Arena Cove, and Santa Cruz, California. The 1960 Chilean Tsunami produced wave heights of 15 feet at Crescent City, California. In 1964, the Alaskan tsunami generated waves of more than 20 feet at Crescent City,California,where it caused 7.5 million in damage and 11 deaths. The Tsunamis also produced waves from 10 to 18 feet along parts of California,Oregon,and Washington Coasts.

Tsunamis are very dangerous and destroy anything in their path. They have also been known to kill hundreds of thousands of people and leave many stranded.