Instead, a collision between two continental plates crunches and folds the rock at the boundary, lifting it up and leading to the formation of mountains and mountain ranges. What happens when two continental plates collide? Because the rock making up continental plates is generally lighter and less dense than oceanic rock, it is too light to get pulled under the earth and turned into magma. They connect divergent and convergent boundaries to form a continuous boundary. If the wave reaches land, it can cause incredible destruction, like the Asian Tsunami, which killed more than 200,000 people in 11 countries across the Indian Ocean region in December 2004. Plates can also move past each other without creation or destruction of crust. A tsunami is a huge ocean wave caused by a sudden shift on the ocean floor, such as an undersea earthquake. Earthquakes generated in a subduction zone can also give rise to tsunamis. Since the collision and subduction of plates is not a smooth process, large, powerful earthquakes are another phenomenon that result from this type of interaction. Examples include the Mariana Islands in the western Pacific Ocean and the Aleutian Islands, off the coast of Alaska. Illustration depicting how island arcs are formed.Ī subduction zone is also generated when two oceanic plates collide - the older plate is forced under the younger one - and it leads to the formation of chains of volcanic islands known as island arcs. These convergent boundaries also occur where a plate of ocean dives, in a process called subduction, under a landmass. Examples include the boundary between the Eurasian plate and the African plate, forming the Alps, and the boundary between the Indian plate and the Eurasian. An example of this is the band of active volcanoes that encircle the Pacific Ocean, often referred to as the Ring of Fire. Examples for island arc systems underlain by. Normally the older plate will subduct because of its higher density. The island arc of this system is separated from the continent by a marine basin underlain by oceanic crust. When this magma finds its way to the surface through a vent in the crust, the volcano erupts, expelling lava and ash. When a convergent boundary occurs between two oceanic plates, one of those plates will subduct beneath the other. Magma rises into and through the other plate. The magma formed at a subduction zone rises up toward the earth's surface and builds up in magma chambers, where it feeds and creates volcanoes on the overriding plate. At convergent plate boundaries, oceanic crust is often forced down into the mantle where it begins to melt.
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