Natural Hazards 3 - Tsunami's

Tsunami

Tsunami

The sudden displacement of a large amount of water caused by eruptions or earthquakes.

Explain how tsunami’s form

The sudden movement of oceanic plates (destructive plate boundaries) can cause the water to surge upwards, and then fall back. The energy that is created by this races under the surface of water and forms a series of waves. These are known as wave trains, which can be tons of kilometers apart.

What is the pacific ring of fire?

It is a path along the Pacific Ocean that has the most volcanic eruptions and earthquakes. Countries that border around the Pacific Ocean are most likely to be affected by Tsunamis (Japan, Indonesia, Philippines).

What are three primary causes of tsunamis?

1) Undersea earthquakes

• the sudden movement of oceanic plate boundaries builds up pressure and releases causing water to surge up and fall back

2) Volcanic eruptions

• The eruptions can trigger a sudden displacement in water which results in a tsunami forming. The debris of dried magma can cause water to displace

3) Underwater landslides

• The pressure that builds up releases energy that goes to the water, displacing it

What tools can be used to monitor tsunamis

Seismic equipment to monitor seismic activity such as underwater boundary movement, and water level gauges to detect abnormal seal level rises. These basically gives off an early warning to tsunamis giving people time to prepare.

Tsunami Waves

The lowest part of the wave (trough) reaches the land first which causes a vacuum effect that brings back the coastal water back to sea. When the wave reaches shallow water near the coastline, the water at the bottom slows down, but the water at the top keeps on moving.

Difference between normal waves and tsunami waves

Normal waves are caused by the wind flow which goes in a circular motion, whereas tsunami waves as caused by energy carried in the water causing a large displacement.

What can people do in a tsunami warning

If possible, people should evacuate, if not they should refrain from low grounds.