ASCENT OF MAGMA
Ascent of magma
DR. T. V. PADMA
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Powerful volcanic explosions can bury cities and change the landscape.
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Volcanoes are some of the most violent of natural phenomena. However, since the days of ancient settlements, people continue to live close to volcanoes near Mt Vesuvius to modern day settlements that crawl up close to volcanic slopes. Powerful volcanic explosions can bury cities and change the landscape. There is obvious danger from hot flowing lava, of course, but there is also less obvious danger, such as from landslides. Eruptions can also change water resources and make the air unbreathable. Tiny drops of sulphuric acid, arising from volcanic eruptions, can even change the climate for short periods!
From deep within
Volcanoes are usually located at places in the earth’s crust where tectonic plates meet. The surface of the earth is made of plates — and places located near adjacent plates are usually subject to stresses that may result in volcanoes or earthquakes. The ascent of magma (molten rock) from deep within our planet to our planet’s crust is what drives volcanic eruptions.
Not all eruptions are violently explosive and dramatic. In some places, magma comes to the surface and flows out quietly, so that a stream of hot lava spreads on the surface. The violence of an explosion depends mainly on the composition of the magma — its viscosity, temperature and the gases dissolved in it, primarily. Geologists classify volcanoes based on their eruptive patterns and forms.
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