Volcanoes can be defined as breaks or cracks on the Earth’s surface which allow the flow of hot lava and other substances such as volcanic ash and gasses. These substances find their way to the Earth’s surface through the magma chamber that lies within the volcanoes.
Global distribution of volcanoes: –
Volcanoes in the Mid-Atlantic belt
- The world’s volcanic structures, including the Mid-Atlantic Ridge, submerge underwater. The volcanic mountain ranges of the Mid-Atlantic Belt, about 90% of them, submerge at a depth of approximately 2500 meters.
- The range previously covered the two hemispheres and was first discovered in the nineteenth century. However, 90% of the mountain range is submerge underwater; the axial of the Mid-Atlantic Ridge is visible in Iceland.
- The convergence point of the tectonic plates that form the floor of the Atlantic Ocean situates the Mid-Atlantic Belt. The molten lava from beneath the Earth’s surface spreads at a slow pace on the ocean floor. Hence, the ridge is considering as “slowly spreading”.
- The range spreads across the north-south axis of the Atlantic Ocean. The volcanic mountain range extends from the Arctic Ocean to the southern tip of Africa. The belt extends at mid-lengths on either side of the continent.
- The volcanic mountain ranges sometimes reach above sea level forming island groups such as:
Due to the slow-spreading process of the Mid-Atlantic Belt, the Atlantic floor is slowly spreading at the pace of 1-10 cms every year.
Circum Pacific Ring of Fire
- The Pacific ‘Ring of Fire’ or Pacific rim, or the Circum-Pacific Belt, is an area along the Pacific Ocean that is characterizes by active volcanoes and frequent earthquakes.
- Volcanic arcs and oceanic trenches partly encircling the Pacific Basin form the so-called Ring of Fire.
- It is home to about 75 per cent of the world’s volcanoes – more than 450 volcanoes.
- Also, about 90 per cent of the world’s earthquakes occur here.
Seismic activity of the region
- The area is along several tectonic plates including the Pacific plate, Philippine Plate, Juan de Fuca plate, Cocos plate, Nazca plate, and North American plate.
- The movement of these plates or tectonic activity makes the area witness abundant earthquakes and tsunamis every year.
- Along much of the Ring, tectonic plates move towards each other creating subduction zones.
- The other plate pushes down or subducts one plate.
- This is a very slow process – a movement of just one or two inches per year.
- As this subduction happens, rocks melt, become magma and move to Earth’s surface and cause volcanic activity.
- The 5 percent of known volcanoes in the world that are not closely related to plate margins are generally regard as intraplate, or “hot-spot,” volcanoes.
- Hawaiian volcanoes are the best examples of hot-spot volcanoes.
- Many times volcanic actions occur inside Plato at the place of plate boundary. Their interpretation has not been possible by plate tectonics. Snack plateau, Paraná plateau, Drakensbarg plateau are important examples.
Location Of Volcanoes,Location Of Volcanoes
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