Strike-slip earthquake focal mechanism

Left hand plot shows a focal mechanism from an earthquake where the fault is horizontal (red line), and the motion is right-lateral strike skip.  The initial direction of wave motion (either back toward the source or away from the source is shown by the arrows.  Right hand plot shows the associated beachball diagram, with compressional (“C”) and tensional (“T”) quadrants labeled.  (Source, wikipedia.com, By Mikenorton - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=4050363)