In order for all links to function properly, you must start by clicking here . Volcano Formation Volcanoes form when hot material from below rises and leaks into the crust. Magma, rising from lower reaches, gathers in a reservoir, in a porous region of overlying rock called the magma chamber . Eventually, but not always, the magma erupts onto the surface. Strong earthquakes accompany rising magma, and the volcanic cone may swell in appearance, just before an eruption, as illustrated in this picture.
Scientist often monitor the changing appearance of a volcano, especially prior to an eruption.
This is a drawing of magma percolating up through the crust, causing the volcano to expand prior to eruption. Volcano Formation Volcanoes form when hot material from below rises and leaks into the crust. Magma, rising from lower reaches, gathers in a reservoir, in a weak portion of the overlying rock called the magma chamber . Eventually, but not always, the magma erupts onto the surface. Strong earthquakes accompany rising magma, and the volcanic cone may swell in appearance, just before an eruption, as illustrated in this picture.