.:Volcano:.

Types and Formation of Volcanoes

Ash and cinder cones: Formed when ash and cinder are violently spewed out form an erupting volcano and blown to great heights. This type of volcano is hardly composed of any lava, most cinder and ash. The ash and cinder cone volcano normally have steep sides and a small crater (e.g. Mount Paracutin in Mexico)
Composite Volcano: Formed by alternating levels of lava, ash and cinder. Eruptions are not as violent as the ash and cinder cones, as lava also escapes from many side vents. Composite volcanoes are high and have gentle slopes at the base but steeper slopes near the top. (e.g. Mount Vesivius, Italy)
Shield Volcano: Forms when eruptions produce runny lava that flows across a vast area instead of making a cone. Shield volcanoes usually have many side vents.
• Majority of volcanic eruptions occur near plate boundaries
• Convergent Plate movement: Most powerful eruptions occur when plates collide, where there is an enormous amount of energy built up in the Earth’s crust
• Divergent Plate movement: Volcanoes can also erupt when plates move apart from each other, but these eruptions are much gentler.

• Hotspots: However, a minority of volcanic eruptions occur because magma rises through fissures and cracks in the Earth’s crust at permanent “hotspots”. In oceanic areas, when magma continuously rises through these cracks, a succession of volcanic islands will form as the tectonic plate drifts over the hotspot.