The Changing World

Volcanic activity is a process in which magma is ejected to the surface of the Earth through its crust. Volcanoes do not occur at random; they form long chains, which are essentially the boundaries of tectonic plates. Volcanic activity has an important role in mountain formation. Volcanic eruptions also affect people’s lives: on the one hand, they destroy the environment and endanger human life, but, on the other hand, they leave behind fertile soil and hot springs.

Geyser

A spring that periodically discharges hot water. Water col­lected in an underground cavity is heated from below by the heat of a magma chamber, then it erupts like a fountain.

Europe’s most dangerous volcano. Its most famous eruption was in August AD 79. The erupting ash, debris and lava buried the cities of Pompeii and Herculaneum and killed their inhabitants.

Mud volcano

Volcanic activity in clay areas are accompanied by ’mud volcanoes’, where gases are released by
liquid mud as bubbles.

Iceland’s infamous volcano:
Its eruption lasted eight months from June 1783. It spewed out vast amounts of lava and ash.
A quarter of the population of Iceland died either from toxic gases or famine following the eruption, which had an effect on the climate of the entire world.

Magma is red-hot, molten rock beneath the Earth’s surface. Magma that flows to the surface is called lava, and a volcano is formed where it reaches the surface.

At divergent plate boundaries there are volcanic cones with a gentle slope.

At convergent plate boundaries, where subduction occurs, the magma of the volcano is derived from the subducting, melting plate, and volcanoes are steeper there.