GEOLOGY

Detailed explanation-1: -As volcanoes erupt, they build up layers of lava that may eventually break the water’s surface. When the tops of the volcanoes appear above the water, an island is formed. While the volcano is still beneath the ocean surface, it is called a seamount. Oceanic islands can form from different types of volcanoes.

Detailed explanation-2: -Most volcanic islands originate from passive lava flows on the seafloor. These passive flows harden into rock and build up the height of the underwater mountain over millions of years. Eventually, some volcanoes reach heights above the seafloor where lower pressure allows for explosive eruptions.

Detailed explanation-3: -Seamounts. Many submarine volcanoes are seamounts, typically extinct volcanoes that rise abruptly from a seafloor of 1, 000-4, 000 meters depth. They are defined by oceanographers as independent features that rise to at least 1, 000 meters above the seafloor.

Detailed explanation-4: -The subduction of the oceanic plate causes the solid mantle material to melt and magma is formed. The magma rises through the mantle and ocean floor to emerge as lava which cools and solidifies to form volcanoes which eventually rise above the sea level to form volcanic islands such as the Mariana Islands.

Detailed explanation-5: -Constructive plate boundary volcanoes At constructive plate boundaries, the tectonic plates are moving away from one another. The Earth’s crust is pulled apart to create a new pathway for rising hot magma to flow on to the surface. Volcanoes can sometimes form in these setting; one example is Iceland.