This is a drawing of magma making it's way up through the crust, causing the volcano to expand prior to eruption.
Click on image for full size
Volcanoes form when hot material from below rises and leaks into the crust.
The hot material, called magma, rising from lower ground, gathers in a reservoir called the magma chamber. Eventually, but not always, the magma erupts onto the surface and forms lava. Strong earthquakes accompany rising lava, and the volcano may swell just before an eruption, as shown in this animation.
White arrows in the picture show the volcano getting bigger as the lava rises inside. Scientist measure the swelling of a volcano before an eruption.
The different reasons why a volcano forms are
- when bubbles of material rise to the surface
- when the crust is forced to go down
Shop Windows to the Universe Science Store!
You might also be interested in:
A "mantle plume" is a bubble of material which rises to the surface from deep inside a planet. The plume is the red portion shown in the drawing to the left. Deep inside a planet it is very hot! Even so,...more
When magma is erupted onto the surface in the form of lava, it becomes silicate rock. With each different eruption of the volcano, lava which comes to the surface is made of slightly different chemicals,...more
This drawing shows another way that islands are made. A rising hot bubble of material finds it's way into the crust of the Earth from the deep interior, and begins to erupt. This bubble or "plume" is called...more
When two sections of the Earth's crust collide, one slab of lithosphere can be forced back down into the deeper regions of the Earth, as shown in this picture. The slab that is forced back into the Earth...more
As the Earth cools, hot material from the deep interior rises to the surface. Hot material is red in this drawing, under an ocean shown in blue green. The hotter material raises the nearby layers, and...more
Mountains are built through a general process called "deformation" of the crust of the Earth. Deformation is a fancy word which could also mean "folding". An example of this kind of folding comes from...more
Many scientists have thought for years that the dinosaurs went extinct because an asteroid hit Earth near Mexico in a place called Chicxulub and caused big changes in the Earth’s climate. Now, scientists...more