This is how the different earthquakes form. All we need is a new, different natural disaster each week and we'll learn tons when I'm here at 4am and bored cause I've read everything I can about the Seahawks on espn.com. This is again off the msnbc page. I'm not smart enough to come up with the big words on my own.
Rift Valley - Continental plates pull apart, allowing the crust to sink.
Mountain Building - Continental plates collide, forcing rock layers to fold and pile up into mountain ranges.
Subduction - Ocean floor is forced under the continental crust and into the magma where it is consumed and recycled. The subduction process is accompanied by the world's strongest quakes, measuring up to 8.9 on the Richter scale.
Sea floor - Balastic magma rises to form new ocean floor along a fault. An undersea ridge is formed which gradually spreads as new material pushes it along its way, accompanied by almost constant earthquake activity. Spreading ocean floor is much thinner than the continental plates but can break the sea surface, forming volcanic islands.
Strike-slip faults - Form where two plates shear past each other. The resulting earthquakes are less powerful than those in subduction zones, but can be more destructive to mankind because their focus is nearer the surface.