Every rumble of 4+ magnitude over more than a century spatter the earth, showing the story of plate tectonics. Data from NCEDC.org and the USGS and UC Berkeley have been sliced out into veneers based on magnitude, then glued onto and image that began it's life at NASA's Visual Earth and wrung into the Times projection (centered at the interesting bits). The result looks an awful lot like a fleet of Nickelodeon tankers spilled the world's supply of floam.