common natural disaster is flooding, which occurs when a river bursts its banks and the water spills out onto the floodplain.
This is far more likely to happen when there is a great deal of heavy rain, so during very wet periods, flood warnings are often put in place.
 There are other risk factors for flooding too: steep-sided channels cause fast surface run-off, while a lack of vegetation or woodland to both break the flow of water and drink the water means that there is little to slow the floodwater down. Drainage basins of impermeable rock also cause the water to run faster over the surface.
Tsunamis can also be caused by underwater volcanic eruptions. Volcanic eruptions are another natural disaster, and they are caused by magma escaping from inside the earth.
An explosion takes place, releasing the magma from a confined space, which is why there are often also huge quantities of gas and dust released during a volcanic eruption.
The magma travels up the inside of the volcano, and pours out over the surrounding area as lava.