Monday, 15 December 2014

What Causes A Tsunami?

Welcome back my fellow learners, today we are going to find out what causes a Tsunami.

Tsunami are massage waves that are created by sudden movement of the ocean, mostly because of such things as landslides and earthquakes on the sea floor, land being dumped into the ocean, and volcanic eruptions or meteorite impacts.

Most tsunami are created by earthquakes on the sea floor, when rocks move past one another suddenly, causing the water to move. The resulting waves are pushed away from the earthquake event.

Underwater landslides and terrestrial land that falls into the ocean can cause a tsunami.

Volcanic eruptions
Less common are tsunami as a direct cause of an volcanic eruption. These happen in different ways.

1. The collapse of coastal, island and underwater volcanoes.
2. Pyroclastic flows, these are hot blocks, pumice, ash and gas, running down volcanic slopes straight into the ocean and subsequently pushing the water outwards.
3. A caldera volcano that collapses after an eruption, which causing overlying water to suddenly drop.

What are tsunamis?
The phrase tsunami, is the Japanese word tsu, which means harbour, and nami, meaning wave. A tsunami are massive waves caused by underwater disturbances, usually in connection with earthquakes which happen beneath or near an ocean. Volcanic eruptions, landslides, and rock falls will also create tsunamis, as will an asteroid hitting the ocean. They begin from vertical movement on the sea floor, with the resulting displacement of a water mass.

In deep oceans, waves have been documented to travel at around 800 km/h, and are only a few centimetres high. In the ocean, waves are created by the wind, and can be noted by their amplitude, this is the height of the wave, and wavelength, this is the distance from crest to crest. 

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