Convergent Boundaries

Question 1

Oceanic to oceanic

Answer 1

2 oceanic plates collide. The heavier plate subducts underneath the lighter one. Magma rises, reaches the surface forming a volcano. Material from these volcanoes build up creating volcanic arc islands. E.g. Mariana Islands in the Pacific Ocean. A deep ocean trench is also formed at the subduction zone. E.g. Mariana trench - subduction of the Pacific Plate under the Philippine Plate (10,000m deep). Friction leads to earthquakes along the boundary. Underwater earthquakes lead to tsunamis.

Question 2

Oceanic to continental

Answer 2

When an oceanic and continental plate collide the heavy oceanic plate is pulled down into the mantle, forming volcanoes, deep ocean trenches and earthquakes. Meanwhile the continental plate scrapes sediment off the seafloor to form layers of rock which with the continent are eventually compressed and buckled into fold mountains.

Question 3

Continental to continental

Answer 3

2 continental plates collide. The movement is upwards creating fold mountains. Trapped sediments on the ocean floor that were between the continents are also involved in this folding. Earthquakes occur at these zones due to great compression of the earths crust. E.g. Indo - Australian plate and Eurasian plate (Himalayas).