Islands (N1); the formation of the island is due tot he intense volcanic activity because of the subduction zone, where one of the oceanic plates moves below the other oceanic plate.
Trench (N2); The trench has formed on the subduction zone itself between the two oceanic plates. The reason for its formation is that gap that has been opened up between the two plates as they interact with one another.
Rift valley (N3); it has formed as a deep underwater valley at the place of divergence between the two oceanic plates. The mid-ocean ridge is right next to it, and its elevation contributes that the rift valley is even more pronounced with its depth relative to its surroundings.
Trench (N4); this trench has formed on the subduction zone between a continental and oceanic plates. The denser oceanic plate is moving below the less dense continental plate, and between the two a gap has been opened. This gap is in the shape of a very deep underground valley, having very steep sides, known as trench.
Volcanoes and mountains (N5); The volcanoes and mountains have formed as part of the subduction between the continental and oceanic plate. The magma has been pushed through the cracks of the crust, so parallel to the boundary, a continental volcanic arc has been formed. Also, the crust has been pushed up as the oceanic plate has been moving below the continental plate, resulting in orogeny and formation of a mountain chain.
