A volcano is an opening in the ground that spits out hot gases, rock and lava. The eruption can be so bad it can blow the top off the mountain.
A volcano is formed when plates hit each other. One of the plates goes under the other. This is where the earth heats and melts the rock into magma and gases. This can happen as deep as 100 miles below the earth. Magma settles in pools or chambers near the surface. This is where eruptions take place.
Volcanoes can also be formed when the plates go away from each other. The magma pushes up and lava forms. These types of volcanoes are found on the ocean floor.
The volcanoes around Hawaii are not created by a tectonic plate, but hot spots. Hot spots are places that have fierce heat in the mantle. This heat causes magma to bubble and move to the surface. The scientists believe that these volcanoes were formed by a column called a mantle plume. These columns measure about 100 miles in diameter and can rise 5 to 10 inches yearly.
Volcanoes are found around an area called "Ring of Fire". This ring circles around the Pacific Ocean. Volcanoes are formed where the edges of the tectonic plates meet.
Volcanoes have been responsible for the greatest disasters in the world destroying towns and killing millions of people.
Lava Example
Things that come out of a volcano:
- Lava - 2012º F--sticky--hardens when cooled
- Rock fragments - sticky magma--pressure breaks it into fragments
- Volcanic dust - 1/400 inch in diameter--can be carried around the globe -- bright red
- Volcanic ash - fragments 1/5 inch in diameter
- Volcanic bombs - size range from baseballs to basketballs
- Gas - mostly steam - with carbon dioxide, nitrogen, sulfur dioxide
Classification of Volcanoes
Active - erupt constantly
Dormant - inactive
Extinct - inactive (probably will not erupt
again)
Intermittent - erupts less than an active
