Earthquakes

=** 3d. Students know why and how earthquakes occur and the scales used to measure their intensity and magnitude. **= media type="youtube" key="CtBXTvtFaCU" height="405" width="500"

An earthquake is a shaking of the ground caused by the sudden breaking and movement of large sections (  tectonic plates  ) of the earth's rocky outermost crust. The edges of the tectonic plates are marked by faults (or fractures). Most earthquakes occur along the fault lines when the plates slide past each other or collide against each other.