a long narrow region, usually adjacent to a continent, along which earthquake foci lie on a plane which dips downwards at about 45° and along which the oceanic lithosphere is thought to be descending into the earth's interior
the discontinuity between the crust and the mantle of the earth, occurring at depths that average about 22 miles (35 km) beneath the continents and about 6 miles (10 km) beneath the ocean floor.
