Imagine that you were given a ship equipped with a device that could measure how deep the water is. You are asked to use this ship to find a subduction zone. What would you look for as you sailed around the world's oceans?
Deep-sea trenches are known to lie seaward of and parallel to adjacent island arcs or mountain ranges of the continental margins. They are closely associated with and found in subduction zones which are locations where a lithospheric plate having oceanic crust slides down into the upper mantle under gravitational forces.
