My topic

In my presentation I will  talk about  volcanoes ( I think that it a very interesting phenomenon to discuss because they are phenomena that act in silence and that can trigger disasters). volcanos are  an opening, or rupture, in a planet's surface or crust, which allows hot magma, volcanic ash and gases to escape from the magma chamber below the surface. Volcanoes are generally found where tectonic plates are diverging or converging. Some types of volcanoes  are : 

-Submarine volcanoes

-Subglacial volcanoes

But the most awesome are volcanoes called "Supervolcanoes" a supervolcano is a large volcano that usually has a large caldera and can potentially produce devastation on an enormous, sometimes continental, scale. The example of this is the Yellowstone volcano.
I would like mention a most famous eruption  ..  the "Mount Vesuvius" ,many people say this is a legend but i think its true.. many exiting  studies are  say the same In the year of 79 AD, Mount Vesuvius erupted in one of the most catastrophic and famous
eruptions of all time burying the cities of Pompeya and Herculomo.Geographers can make maps showing areas at risk in the event that a volcano erupts  to help prevent people from falsely believing they are not at risk when living on or near a volcano, countries have adopted new classifications to describe the various levels and stages of volcanic activity.

About the reality national.
Chile have more than 3000 volcanoes, of which 500 of them are active. An example of how devastating these phenomena was the Volcano Explosion "Chaiten" which caused the destruction of the village.                                                                                                     

A panoramic view of the Irazú Volcano ( Costa Rica )