Question

Explain why a volcano is likely to explode more violently if it has been dormant for a long time?

Explain why a volcano is likely to explode more violently if it has been dormant for a long time?

Please help :D

Thanks!!!

Answer 1

Larger accumulation of energy and a plugged conduit

Explanation:

A dormant volcano is slowly "recharging" in the sense that both magma and gases are building up pressure deep within the magmatic chamber.

Moreover the conduit connecting the magmatic chamber to the crater is likely totally plugged by solid lava from the previous eruptions.

Once the pressure inside the magmatic chamber override the lithostatic one (the pressure generated by the accumulated rocks above the chamber) an eruption happens.

Because of the large amount of stored energy such eruptions are often dramatic and extremely violent. An example is the Mt. St. Helens eruption of 1980 in the USA or, even more famous, the eruption of the Vesuvius in 79 A. C. that destroyed Pompei and was recorded by the historic Plinius who also lost his life during the event. This kind of eruptions are called "Plinians" in his honor.