Focal Mechanisms Explained: What are those “beach balls”? (Educational)

www.iris.edu/earthquake for more intro animations
Focal mechanisms are released after an earthquake to show what type of Earth movement produced the earthquake. These are typically shown using a so-called "beachball" diagram. They refer to the orientation of the fault plane that slipped and the slip vector, and are also called fault-plane solutions.
Directed by Robert Butler, geophysicist, University of Portland
Animation & graphics by Jenda Johnson, Earth Sciences Animated
Narration: Roger Groom, Mount Tabor Middle School, Portland OR
Dr. Geophysics character: Richard Blakely, geophysicist, U.S.G.S.

Music: "Constellation" by Water Strider (http://www.waterstridermusic.com)
"Diagonal Stride" by Fadin' by 9 (http://www.fadinby9.com) written & fiddled by Seth Moran, seismologist U.S.G.S.

Reviewed by Anna Courtier, James Madison University, Harrisonburg VA
For more Earth-science animations, visit www.iris.edu/earthquake