What happens before a volcano erupts?

Answer 1

When the magma gets close to the surface, the gases dissolved in it start to come out, forming gases which help the magma rise further and erupt. If there is a lot of gas in the magma, it may explode as the gases expand. There may also be triggers like a landslide that uncaps the magma reservoir (like at Mt. St. Helens in 1980) or an interaction with groundwater that causes an explosion.

Answer 2

They first give off warning signs.

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The magma moves into this place that is called (here at least) a waiting chamber. Here, it gives off gasses, volcanos also cause quick earthquakes or vibrations.

Magma gathering in a chamber causes slight swelling of the volcano's slopes. Gases released near the volcano can be measured for changes or in quantity.

Hope you got all that ^_^

Answer 3

Before a volcano erupts, there are typically signs of increased seismic activity such as earthquakes, deformation of the volcano's surface, and gas emissions. This is often preceded by a build-up of magma beneath the surface, which creates pressure that eventually results in an eruption. Monitoring these signs allows scientists to issue warnings and evacuate nearby areas to prevent loss of life.

Answer 4

magma crawls from underground to an opening in the volcano