VOLCANOES by Alejandro Rigalli

The Romans thought fire was God. They gave it the name of Vulcan; from this name we get the word “volcano”.

The Earth’s crust is divided into large sections, called tectonic plates that fit together like pieces of a puzzle. Many of the active volcanoes on earth can be found along these plates boundaries. The “Ring of Fire” is a 40,000 km area of the Pacific Ocean where 90% of all the volcanoes are.

It takes a long time for a volcano to grow big; most are 10,000 to 100,000 years old. About 1,900 volcanoes on earth are considered active and are likely to explode again.

Volcanoes are mountains that are formed when magma (molten rock) from inside the Earth erupts to the surface. The roots of volcanoes lie 40 to 120 miles inside the Earth in a layer called mantle. Temperatures there are as hot as 4000° F, so hot that rock melts like a chocolate bar on a summer day. The hot, melted rock becomes a thick, flowing substance called magma.

Magma is located in a place called “magma chamber”; this substance is lighter than the solid rock surrounding it and because of pressure, it pushes up through cracks in the Earth.

When the pressure is too great, the magma rushes to the surface through a vent and the volcano erupts. Hot gases form clouds of steam that rise into the air. Ashes mix with the gasses and big pieces of rock may fly out of the hole or crater. Hot liquid also pours down the sides of the volcano, this is known as lava. Lava can reach 1,250°C and has the potential to burn everything in its path.

Volcanoes come in many shapes, sizes and degrees of explosive force. Some common types of volcanoes are:

*An active volcano is a volcano that has had at least one eruption during the past 10,000 years. An active volcano might be erupting or dormant.

*An erupting volcano is an active volcano that is having an eruption...

*A dormant volcano is an active volcano that is not erupting, but supposed to erupt again.

*An extinct volcano has not had an eruption for at least 10,000 years and is not expected to erupt again in the near future.

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