Four thousand of these earthquakes occur in Alaska alone. Alaska happens to be located over a subduction zone, which is where one plate is sliding over another. The largest earthquake the U.S. has ever experienced was in Alaska. Earthquakes are quite common natural events, contrary to what some people might believe. They can occur as deep as 5,000 miles below the surface.
Seismologists are scientists who study earthquakes.
They use two different names to describe the types of waves that are given off by the earthly vibrations. The first is a P-wave, primary preliminary waves, which is the first to arrive at a seismic station after movement. It compresses and dilates the rock as it travels. The speed is comparable to that of sound waves. These waves shake the rock sideways as it advances at half the speed of a P-wave.