This brings us to the next part of the topic, fault lines. Fault lines are the boundaries between tectonic plates. We find most of the earthquake activities occurring at fault lines. “From an earthquake's point of view, there's more than one way to destroy a city. Most earthquakes occur along fissures in the planet's surface called faults. These cracks may be small and limited or can stretch thousands of miles where tectonic plates meet. Usually, the rocks on either side of the rupture are moving past each other too slowly for us to notice, but sometimes stress (pressure) builds up and they'll suddenly slip, making a big move all at once. The effect of that sudden move depends on the type of fault the movement occurs in” (“Fault” 1).
When this sudden slip happens it causes a wave of energy called seismic waves. Seismic waves erupt from a focus point and travel across the earth’s crust. “The point where the energy is released is called the focus and the focal depth is the depth underneath the earth's surface where the energy release was created. The epicenter is another word used in studying earthquakes and this is the point on the earth's surface directly above the focus. From here, the energy is released spreads out in rings moving through the surface - not unlike those