Volcanoes erupt because of density and pressure. The lower density of the magma relative to the surrounding rocks causes it to rise (like air bubbles in syrup).
When a part of the earth's upper mantle or lower crust melts, magma forms. A volcano is essentially an opening or a vent through which this magma and the ...
A volcano begins as melted rock (magma) which rises from deep inside the earth toward the surface. As the gas-filled magma rises ...
Aug 4, 2015 ... It is increased magma movement within a volcano that causes an eruption. These movements are triggered by different processes that happen ...
Find out what the earth make-up is, and how extreme pressure build up inside the ... molten matter to be expelled out to the surface, causing a volcanic eruption.
Jan 5, 2015 ... The eruption of a volcano can be one of the planet's most destructive events — spewing huge amounts of rock, gas and ash that can kill people.
A secondary school revision resource for GCSE Geography covering key facts about volcanoes and volcanic eruptions.
Jan 6, 2016 ... A team of volcanologists led by the University of Liverpool have released a perhaps controversial Nature study on the causes of volcanic ...
Nov 27, 2003 ... "One of the central problems of volcanoes is: Why do they erupt and why ... At the same time, the loss of dissolved gases makes it more difficult ...