3. Volcano

   The activity of the Earth manifests through volcanoes, hot springs and earthquakes.
   If an opening or crack in the earth's crust occurs, the molten material inside the Earth rise to the surface, resulting in a volcano.
   Volcano is the rupture which allows the materials placed in the Earth's interior escape. Conical mountains are usually formed. The parts of the volcano are:
   - The volcanic cone: it is a hill formed by lava.
   - The volcanic pipe: it is the conduit where materials are ejected.
   - The volcanic crater: it is the mouth where the pipe ends.
   There are inactive and active volcanoes. Vesuvius volcano (Italy) was apparently extinct but it activated and destroyed the city of Pompeii.
   Volcanoes are usually located near the seas. The most important are those that form the “Pacific Ring of Fire “.

   4. Choose one of the parts of the volcano and answer: cone, pipe or crater:

    5. The hot springs

   They are springs of heated water that usually have healing benefits.
   When intermittent discharges of water are ejected, it is called geysers. Some of them reach 150 meters high in Yellowstone National Park in the United States

6. Earthquakes    They are jerky movements of earth's crust. In general they are very violent and last about one second. They happen when two blocks of the earth suddenly slip past one another. The surface where they slip is called the fault.    The region where the movement originates is called the hypocenter. The depth of focus does not reach 30 km. From the hypocenter, concentric waves that reach the earth's crust spread. (See the side picture).    The region of the Earth's surface closest to the hypocenter is called the epicenter. When the focus is on the sea is called tsunami. The instruments that measure earthquakes are called seismographs.