On land, volcanoes form when one tectonic plate moves under another. Usually a thin, heavy oceanic plate subducts, or moves under, a thicker continental plate. When enough magma builds up in the magma chamber, it forces its way up to the surface and erupts, often causing volcanic eruptions.
What are 3 ways a volcano can erupt?
Although there are several factors triggering a volcanic eruption, three predominate: the buoyancy of the magma, the pressure from the exsolved gases in the magma and the injection of a new batch of magma into an already filled magma chamber.
What are the 4 ways a volcano can erupt?
- Hydrothermal eruption. An eruption driven by the heat in a hydrothermal systems.
- Phreatic eruption. An eruption driven by the heat from magma interacting with water.
- Phreatomagmatic eruption.
- Lava.
- Strombolian and Hawaiian eruptions.
- Vulcanian eruptions.
- Subplinian and Plinian eruptions.
What are 4 signs that a volcano is about to erupt?
- An increase in the frequency and intensity of felt earthquakes.
- Noticeable steaming or fumarolic activity and new or enlarged areas of hot ground.
- Subtle swelling of the ground surface.
- Small changes in heat flow.
- Changes in the composition or relative abundances of fumarolic gases.
How a volcano erupts step by step?
Magma is lighter than rock so rises towards the Earth's surface. As the magma rises, bubbles of gas form inside it. Runny magma erupts through openings or vents in the earth's crust before flowing onto its surface as lava. If magma is thick, gas bubbles cannot easily escape and pressure builds up as the magma rises.