Volcanoes are mountains with a large hole on top through which magma (red-hot liquid rocks from the earth’s interior) emerges through the crest and on to the surface above.
The word Volcano is derived from Vulcan, the Roman God of fire. There are eight kinds of volcanoes, namely
- Shield Volcanoes,
- Fissure Volcanoes,
- Composite Volcanoes,
- Cinder Cones,
- Strombolian eruptions,
- Vulcanian Eruptions,
- Pelean Eruptions,
- Plinian Eruptions, the last one is the most explosive kind of eruption.
An explosive eruption is driven by expanding bubbles of carbon dioxide gas and steam inside the magma. It blasts hot magma, ash, cinder, gas and steam high up into the air.
According to a statistic, there are about 60 major volcanic eruptions each year around the world. Krakatau is an island in Indonesia. Its eruption on Aug. 27, 1883 in the Sundae straits between Sumatra and Jawa kicked up sea waves almost 40 meter high in which over 36,380 people in 163 villages were washed away! This eruption was heard in many countries around the world. Volcanic mountains under the sea, when erupted, can trigger off tsunami!
According to a study, there are about 1500 possible volcanic eruptions identified, of which over 600 occur around the world each year. There are many undersea volcanoes in the Pacific Ocean, termed as “Ring of fire,” known as Mount Pinatubo off the coast of Philippines and Mount St. Helens in Washington DC. (DC refers to Districts of Columbia).
It is said that the movement of the Pacific plate caused the formation of a chain mountains about 6000 km long. Mount Vesuvius that erupted on Aug. 24, 79 AD blanketed Pompeii, a Roman town with ashes. It had destroyed the town. However, in the 18th century it was rediscovered, buried under some meters of ashes!
How they predict volcanic eruption is that, the satellite 3D radar’s interferometer, an instrument that detects the tiny swell on the volcanoes, cautions about the impending eruptions.