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Most volcanoes are located on the continents edges, along island chains or beneath the sea forming long mountain ranges. More than half of the world’s active volcanoes above sea level encircle the Pacific Ocean to form the circum-Pacific “Ring of Fire.” The ring of fire makes up seventy five percent of the worlds dormant and active volcanoes. More than half of the world’s active volcanoes above sea level are part of the ring. The Ring of Fire is an arc of volcanoes that stretches from New Zealand all the way across the coast of North and South America. This area got its name because there is a great amount of volcanoes that encircle the Pacific Ocean. The ring of fire is known for frequent earthquakes and volcano eruptions. This area of volcanic and seismic activity was noticed and described before the invention of the plate tectonics theory. Around the ring of fire the Pacific plate is colliding with and sliding underneath other plates. This area is known as the subduction zone. The energy that is generated by these plates is tremendous.
The Ring of Fire is the location where most of the seismic activity in the world is taking place. The Pacific Ocean has a mid- oceanic ridges and is surrounded by subduction zones. The spreading rates of the ridges are very fast, resulting in the subduction zones destroying a great amount of the Earth’s crust. This is why there are so many earthquakes and volcanoes all around the rim of the Pacific Ocean, where the subduction zones are located. The energy is so great that it can easily melt rocks into magma. The Ring of Fire is a great example of plate boundary volcanoes.
The major volcanic regions in the Ring of fire are: the Cotopaxi and Azul volcanoes located in South America, the Popcatepetl and Paricutun volcanoes that are found in Central America, Mount St. Helens in the United States, and Mt. Fuji in Eurasia.The Cotopaxi and Azul volcanoes were created by the Nazca and the South American plates colliding together creating the Andes Mountains. In Central America the Cocos and North American plate collided together forming the Mexican volcanoes Popcatepetl and Paricutun. In Northern California and all the way to British Columbia the Pacific, Gorda, and the Juan de Fuca plates collided and the Cascade Mountains are the result.
The Cascade Mountains are where Mount St. Helens is located. The Alaskan Aleutian Islands are continuing to grow as the Pacific and North American plate hit each other. The Aleutian trench was formed as a result of the two plates colliding. The trench was formed at the subduction zone and is 25,194 feet deep. The collision of the Pacific plate under the Eurasian plate has created the Japanese islands where Mt. Fuji is located. In the last area of the Ring of Fire the Indo-Australian plate goes under the Pacific plate and has created the volcanoes in New Guinea and the Micronesian Islands.
The tectonic theory states that the surface of the Earth is made up of gigantic rigid plates that float slowly on top of Earth’s hot interior. Volcanoes are more likely to form where plates collide or spread apart they also can form in the middle of a plate. The plates are about fifty miles thick. The plates change size and position over time. The plates move at about the same speed as a fingernail growing. There is constantly new sea bed forming in the middles of oceans as a result of the hot flowing magma cooling when it comes in contact with the oceans water. The Earth’s plates are constantly moving to make room for the new crust that is being formed. As the plates move there is a great amount of activity that takes place. Sometimes the plates will move away from each other and gap is created leaving space for the new crust, or some of the plates move towards each causing one plate to go on top of the other, and then other slide past each other causing no interruption at all.
When the plates slide past each other in opposite directions there is a chance a minor earthquake could occur and a small chance that the faults might create cliffs thousands of feet high in the ocean bed. The plates that go underneath each other, the plate that is underneath experiences a great amount of heat and the plate begins to melt causing magma to rise and form chains of volcanoes, such as the ring of fire. The subduction zone is known to have big earthquakes and deep ocean trenches. If an earthquake occurs under the ocean, onside of the ocean floor will drop downward allowing the subducting plate to go on top. When an earthquake does happen on the ocean floor it is very likely that a tsunami will happen, and there is little warning to those that are in the path of the tsunami, like we saw in December 2004.
The plate tectonic theory and sea floor spreading offer scientists a better explanation of the Earth’s movement. There are three different types of boundaries that can be recognized between these moving plates. They are: Divergent or spreading, Convergent, and transform fault. In divergent or spreading plates that are adjacent of each pull apart causing sea floor spreading and allowing new matter to be added to the ocean plates. Convergent movement is when plates that move in the opposite direction meet up and one is forced underneath the other.
A good example of convergent movement is the Aleutian Trench. This is where the Pacific plate is forced underneath the North American plate. Transform fault is best described as one plate sliding horizontally past the other. A great example is the San Andreas Fault. This fault line is the boundary marker between the Pacific and North American plates. Many of Earth’s volcanic activities occur along the subduction boundaries at continental plate and oceanic plate convergence or oceanic plate and oceanic plate convergence. Another area is along sea floor spreading in the centers if the ocean floor, or areas of rifting on continental plates, and the final area is at hot spots where there are individual plumes of magma that rise to the surface.