1. The Volcanoes
2. Examples of the phases
3. The Earthquakes
Volcanoes are very dangerous for humans. That’s why, they have always been studied.
The Earth has got 4 layers:
- the inner core: it is a solid layer in the centre of the Earth. The temperature is higher than 1.500°;
- the outer core: it is a liquid layer;
- the mantle: it can be a solid rock or a liquid rock called magma: so it is semi-molten;
- the crust: it is a solid layer and it is divided by the plates. Plates are large and thin pieces of rock.
When a plate cracks the crust, there is a volcanic eruption: the magma goes to the surface and it is called lava (lava is less hot than magma). A volcano generates after a lot of volcanic eruptions.
How is a volcano formed?
- 1. The magma chamber is under the crust and it contains the magma
- 2. The magma goes to the surface through the pipe (a tube)
- 3. The pipe goes in surface and it is called vent
- 4. There are a lot of vents
Scientists divide the volcanoes in 3 groups:
- The active phase when the volcano is erupting or it has recently erupted
- The dormant phase when the volcano has not erupted for many years but the scientists think that it will erupt
- The extinct phase when the scientists don’t think that the volcano will erupt in future
A. Active Phase: Mount Etna
Mount Etna is the highest active volcano in Eurasia. It is near Catania, in Sicily. Every year it erupts and, for this, the territory is continuously changing; for example, in 1669, it destroyed 10 villages with lava. Now, Mount Etna is a UNESCO World Heritage.
B. Dormant Phase: Mount Vesuvius
Mount Vesuvius is one of the most famous volcanoes in the world. It is know for its big eruption in AD 79 when it destroyed a lot of roman towns: for example Pompeii and Hercolanum. Now, these towns are UNESCO World Heritage because they are almost intact. The last eruption was in 1944 and scientists think that in 100 years there will be another eruption
C. Extinct Phase: Crater Lake
Crater Lake is an American “Caldera” lake. A caldera/crater lake is an extict volcano where there is some water. It is in Oregon and it is 1883 m on the sea level. It has also a depth of 594 m, so it is the deepest lake in U.S.A.
When a plate is moving an earthquake can occur. A earthquake is a movement of the surface of the earth. Scientists use the Richter Scale to measure earthquakes. This scale has got 10 numbers and from fourth the seismometer (the instrument that measures the earthquake) can measure the earthquake.
In the center of Italy there have been a lot of earthquakes every day since August 24th 2016. They destroyed a lot of cities and they killed about 200 people, but Italians helped the dispaced and now the cities are rebuilt.
When an earthquake is forming, a tsunami can occur. Tsunamis are a series of traveling ocean waces of extremely long length. These tsunamis are very dangerous because if there is one near the coast of a city, this can be destroyed by the tsunami. For the safe, in case of tsunami a Warning is created in order to save the population.
- Sources provided by the teacher