Question

how volcanoes erupt and earthquakes occur

Answer 1

Where tectonic plates meet, the Earth's crust becomes unstable as the plates slide past each other, push against each other, or ride under or over one another. Earthquakes and volcanic eruptions happen at the boundaries between plates. Magma (molten rock) is less dense than the crust.

Answer 2

Volcanic activity

Volcano
Where tectonic plates meet, the Earth’s crust becomes unstable as the plates slide past each other, push against each other, or ride under or over one another. Earthquakes and volcanic eruptions happen at the boundaries between plates. Magma (molten rock) is less dense than the crust. It can rise to the surface through weaknesses in the crust, forming a volcano.
Geologists study volcanoes to try to predict future eruptions. Volcanoes can be very destructive, but some people choose to live near them because volcanic soil is very fertile.
Earthquakes

Emergency services searching for survivors
The movement of tectonic plates can be sudden and disastrous, causing an earthquake. It is difficult to predict exactly when and where an earthquake will happen, even when a lot of data is available.
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