Each year, there are about a million earthquakes around the world. But only about 100 of these cause serious damage.
An earthquake can trigger a volcano to erupt.
Sometimes there are many small earthquakes before the big one. These small ones are called foreshocks. After the big earthquake, the mainshock, again there may be many small quakes. These are called aftershocks.
Steel, reinforced concrete and wood are good building materials for an earthquake resistant house because they flex somewhat without breaking. Family homes built completely out of brick are not as safe because they can break apart easily.