Natural Disasters – Volcanic Eruption
- Volcanic Eruption happens when the molten rock from inside the Earth flows into the surface.
- Volcanic Eruption is caused by the Earth’s internal heat, and is associated with tectonic processes and is a part of the rock cycle.
- A volcano is a vent through which molten magma and gases are discharged to the surface.
- Volcanos can be formed when the rock near the surface becomes hot enough to melt.
- This often happens in in locations which are also plate boundaries.
- In a divergent boundary, such as at mid-ocean volcanic ridges, material from Earth’s interior slowly rises up, melts when it reaches lower pressures, and fills in the gap.
- Chambers of magma may form in places where one plate is being subducted under another.
- These magma bodies feed the volcanic islands which help mark the locations of subduction zones.
Significance of Volcanoes:
- The presence of volcanos on Earth tells us that Earth’s interior is circulating and is hot enough to melt rocks.
- Earth is constantly cooling and volcanos are one way to lose heat.
- The pattern of distribution of volcanos on Earth gives us a clue into the is divided into plates on Earth’s outer surface.
- The chains of volcanos associated with mid-ocean ridges and subduction zones mark the edges of tectonic plates.
Types of Volcanoes
- These are not very steep but are far and wider and extend to great height as well as distance.
- Lava erupts commonly from vents along fractures aka rift zones, that develop along the flanks of the cone.
- These volcanoes are made up of basaltic rocks which are less viscous and is very fluid during eruption.
- They are generally not very explosive, but may turn explosive if water gets into the vent somehow.
Cinder Cone Volcanoes
- These are small volcanoes formed by loose, grainy cinders which are extrusive igneous rocks and almost no lava.
- Cinder cones are the simplest type of volcano and have very steep sides and usually have a small crater on top.
- They are cone shaped with moderately steep sides and having small craters in their summits.
- They are characterized by the eruption of a cooler and more viscous lava than basaltic volcanoes.
- The deterministic feature of a composite volcano is the presence of a conduit system through which magma from a reservoir deep in the Earth’s crust rises to the surface.
- The material accumulates in the vicinity of the vent openings which leads to the formation of layers, and this gives them their alternate name as stratovolcanoes.
- They are the most explosive type of volcanoes on Earth.
- Their eruptions result in them collapsing on themselves rather than building any tall structure.
- They gained their name from these collapsed depressions which are also called as calderas.