ULTIMATE GUIDE TO TSUNAMIS

The word tsunami triggers images of larger than life waves striking land and rolling inwards to cause monumental levels of damage. The recent Japan earthquake and subsequent onset of tsunamis has reminded the human race of the sheer destructive power of water, nature’s greatest element.
Tsunamis are usually not just one, but a series of waves caused by a major disturbance in ocean and sometimes in large lakes. This disturbance displaces a large volume of water which due to its colossal force causes destruction when it hits land

Science Behind Tsunamis
There are multiple causes behind tsunamis. Earthquakes have been the most recent cause, however tsunamis can also occur due to other major movements such as landslides and oceanic impacts like meteorite collisions.
Earthquakes, Volcanic Eruptions and Underwater Explosions: When two continental plates are placing force on one another, the shifting of these plates not only causes an earthquake but sudden displacement of water resulting in a tsunami. Volcanic tsunamis may occur when the constant flow of magma from the volcano empties the chamber in which the magma was originally in. The volcano then caves upon itself causing the water to surge inwards resulting in a tsunami.

Landslides and other Mass movements: A large enough landslide into a significant body of water will displace the water and can cause a tsunami. This is often compared to throwing a stone into water. Landslides causing tsunamis may occur underwater as a result of an earthquake, explosion or other large movement.

Meteorite and Other Oceanic Impacts: Once again, similar to throwing a rock into a pond, a large meteorite hitting the ocean would cause a tsunami due to the force of impact.

Tsunamis are not often very high when in the ocean. However, as they come closer to land and into shallow water the energy is concentrated into a smaller volume and the wave's power can overwhelm whatever is in its path.  In shallow water, it slows down and the amplitude can increase to dangerous heights, sometimes 50 feet or higher.

In the ocean, a tsunami may only be 1 metre high, however as it hits landfall the height may increase to hundreds of metres.
The tallest recorded tsunami occurred in the 1958 Alaska earthquake reaching 520 metres. This tsunami occurred from 30.6 million cubic metres of rock that were loosened which plummeted 914 metres before hitting the Gilbert inlet.

The Science Behind Tsunamis: A look at tsunamis from Japans 2011 event 
Background Information on our Changing Earth: Teacher resources for K-12 on geography including tsunamis

How to Survive A Tsunami
Surviving a tsunami means being aware of the warnings that are issued by systems put in place by scientists and the government. The important words to understand are for these warnings are:
Advisory: This is issued when an earthquake has struck which may cause a tsunami.
Watch: This is issued when a tsunami may have been generated but it may or may not hit the coast.
Warning: This is issued when a tsunami has been issued and will most likely strike the coast. At this point, one must evacuate.
If you live in an area that may be hit by a tsunami it is important to know whether your home is in the tsunami danger zone. Evacuations are usually performed based on two numbers, the height of land and the distance from the ocean. Knowing these two numbers may help you determine if you need to evacuate or not.
In the event that your area is issued a tsunami warning, try to use a preplanned evacuation route. Make sure to keep listening to warnings broadcasted over the radio. If you do not have enough time to evacuate get to high grounds such as the roof of a multistory building. Two story buildings may not be high enough to withstand the power of a tsunami especially if they are near the ocean. If you get stranded in a flooded area tie a bright sheet outside the structure to signal for help.

Tsunami Safety Tips: National geographic tips to survive tsunamis.
Tsunami Safety: Making a plan, getting a kit ready and being informed.
Safety Tips for Dealing with a Tsunami: 6 tips to keep your family safe.
International Preparedness Network: Preparing you for tsunamis.

Notable Tsunamis throughout History
The following are the six most recent, notable tsunamis in modern history:
March 2011: Japan’s largest earthquake since records have been kept at 8.9 caused a tsunami leaving thousands dead. The tsunami travelled across the Pacific Ocean hitting Hawaii followed by the US West Coast.
December 2004: The Sumatra-Andaman earthquake with a magnitude of at least 9.1 near Indonesia caused a tsunami that travelled as far as Nova Scotia and Peru. An estimated 230,000 people died, mostly from the tsunami and difficulty in delivering aid afterwards.
July 1998: An earthquake of magnitude 7.1 caused a tsunami in Papua New Guinea killing 2,200 people.
Aug 1976: Philippines lost 8,000 lives from a tsunami caused by an earthquake that was at least 7.9 on the Richter scale
March 1964: More than 120 people were killed in Alaska by a tsunami caused by an 8.4 earthquake. 10 people also died in northern California from the same tsunami.
May 1960: Chile had the largest recorded earthquake at a magnitude of 8.6 which caused a tsunami killing 1,500 people there and in Hawaii.

Links to Resources
Tsunami and Earthquake Research at the USGS: Events, starting points, research studies and past event.
Tsunami…Tidal Waves: Course notes for tsunamis.
Tsunamis: An introduction to tsunamis.
Waves of Destruction: All about tsunamis.
Earthquakes, Volcanoes, and Tsunamis: Web resources for creating a multimedia scrapbook
Japan’s Earthquake and Tsunami Facts and Figures: All about the 2011 natural disaster that Japan has faced