What amount of damage is caused by an earthquake?

There's a lot of damage when a earthquake occurs (happen) houses fall also when earthquakes happen there's some volcanoes near it. When earthquakes happen then they form volcanoes. If you want to know what tectonic plates are ill tell you they are plates that form volcanoes when one plate goes under another it forms a mountain with magma in it and also the plate that went under the other one is melts into magma. Its like a machine