The term 'origins of earthquakes' can be summarized by the four-letter word FOCI, which stands for 'FOCI, ' or the plural form of 'FOCUS.' FOCI are the points within the Earth's crust where seismic waves originate from. Earthquakes occur when two tectonic plates slip past each other, releasing energy in the form of seismic waves that travel through the Earth's crust. The epicenter of an earthquake is the point on the surface of the Earth directly above the FOCUS.