atheistangel:Good Vibrations.When a 6.8 earthquake shook Olympia, Wash., in 2001, shop owner Jason W
atheistangel:Good Vibrations.When a 6.8 earthquake shook Olympia, Wash., in 2001, shop owner Jason Ward discovered that a sand-tracing pendulum in his shop had recorded the vibrations of the earthquake on the sand. Seismologists say that the “flower” at the center reflects the higher-frequency waves that arrived first; the outer, larger-amplitude oscillations record the lower-frequency waves that arrived later -- source link