TSUNAMI

Remember what hapend in Aceh on December 2002? It was a tsunami at indian ocean at the west coast of the northern Sumatra that Killed about 200,000 more people.
But what is Tsunami is? what coused it?

Tsunami is a Japanese word: 'tsu' meaning harbour and 'nami' meaning wave. Tsunami are waves caused by sudden movement of the ocean surface due to earthquakes, landslides on the sea floor, land slumping into the ocean, large volcanic eruptions or meteorite impact in the ocean.

Until recently, tsunami were called tidal waves, but this term is generally discouraged because tsunami generation has nothing to do with tides (which are driven by the gravity of the Earth, Moon and Sun). Although some tsunami may appear like a rapidly rising or falling tide at the coast, in other situations they can also feature one or more turbulent breaking waves.

A tsunami is different from a wind-generated surface wave on the ocean. While wind-generated waves in deep water only cause water movement near the surface, the passage of a tsunami involves the movement of water from the surface to the seafloor. Interestingly, this causes the speed of a tsunami to be controlled by the water depth, with faster speeds in deeper water, unlike wind-generated waves. Consequently, a tsunami slows as it approaches land and reaches increasingly shallow water, with the distance between successive wave peaks decreasing. Because the total energy within the wave does not change, the energy is transferred to increasing the wave height (or amplitude). This is called wave shoaling.

Most tsunami are caused by large earthquakes on the sea floor when slabs of rock move past each other suddenly, causing the overlying water to move. 

this is how tsunami it happens:

1. a continental plate is dragged down and bent by an oceanic plate.

2. the continental plate cannot bend anymore and snaps back, pushing the sea water up.

3. the seawater spreads in all directions as a tsunami and reaches land

Tsunamis occur due to natural movement co we cannot stop tsunami.So what can we do? simple, just study hard and get a better education, maybe in a few years, Indonesia will have technology to prevent tsunami, like Japan did.

source : Ted-ed how's tsunamis works/youtube