Stoneley Wave
Stoneley Wave : Wave trapped at a plane interface of two elastic media. It is always possible at a solid-fluid interface with the phase velocity lower than the Compressional velocity of the fluid. It can exist at a solid-solid interface only in restrictive cases. See Aki and Richards (2002 or 2009, p. 156-157), as well as Webb (2002), and the biography of Robert Stoneley in Howell (2003)