Tsunamis• Giant waves generated by an underwater

disturbance that cause destruction to coastal areas

• Japanese for“harbour wave”

• Often incorrectlycalled “Tidalwave”

Tsunamis

• Waves will travel outward in all directions• Time between wave crests may be from 5

to 90 minutes• Wave speed in the open ocean will

average 450 miles per hour. • Heights of over 100 feet recorded

Tsunamis

• When created, it has a very long wave length and short wave height.

• As it approaches shallow coastal waters, length is compressed and heights are increased

• Wave becomes unbalanced and topples

Tsunamis

• Rapid changes in the water level are an indication of an approaching tsunami.

• Arrive as a series of successive crests (high water) and troughs (low water)

• After a severe earthquake on November 18, 1929, in the Grand Banks of Newfoundland – generated a tsunami that caused

considerable damage and loss of life at Placentia Bay, Newfoundland.

- Triggered by a 9.3 underwater earthquake off the coast of Indonesia

- Killed over 230 000 people- A series of deadly waves up to 30 m high- One of the deadliest natural disasters in human history

Boxing Day Tsunami

Boxing Day Tsunami

Tsunamis – Kalutara, Sri Lanka- Before

Tsunamis – Kalutara, Sri Lanka- After

Tsunami - Banda Acech – Northern Sumatra - Before

Tsunami - Banda Acech – Northern Sumatra - After

Predicting TsunamisIt can be difficult to predict a tsunamiA sharp swell is the first sign, followed by a

receding shorelineThen the first massive wave hits. The third to

eighth waves are usually the largestOne of the best ways to predict a tsunami is

to monitor earthquakes

Survive it!In groups, brainstorm and research ways to

survive either an earthquake OR a tsunami.Could include structural changes to

buildings, or survival kits