Watch the seismic waves from the M7.3 earthquake in Japan cross North America. This animation, called a Ground Motion Visualization (GMV), shows the motion of the ground as detected on seismometers across North America - each dot is a seismic station and when the ground moves up it turns red and when it moves down it turns blue. Waves generated by an earthquake travel around and through the earth, but they get smaller (attenuate) as they move away from the earthquake location, just like ripples