On regional basis, various factors are responsible for the origination of vulcanicity in the world.
Following are the major factors visible in the world:
1. Isostatic Disequilibrium: In isostatic regions, structural changes take place due to isostatic disequilibrium. This gives rise to vulcanicity.
2. Formation of Gases: Isostatic water enters in the internal part of the earth through ridges and transforms into vapor which work as propulsive force in eruption.
3. Increase in Temperature of the Earth’s Crust: Heat evolved by continuous fission o£ radioactive substances inside the earth’s crust causes the rocks to weaken and increase in volume. After this, lava erupts out of the weakened cracks.
4. Decline in Pressure: Due to the pressure of upper layers, the rocks inside the earth’s crust remain in solid condition and they melt on decrease in pressure which encourages vulcanicity.
5. Plate Tectonic: Vulcanicity also takes place due to the movements of various tectonic plates. Vulcanicity further intensifies if the plates move in opposite direction of one another.