GEOLOGY

Detailed explanation-1: -Atolls develop with underwater volcanoes, called seamounts. First, the volcano erupts, piling up lava on the seafloor. As the volcano continues to erupt, the seamount’s elevation grows higher, eventually breaking the surface of the water. The top of the volcano becomes an oceanic island.

Detailed explanation-2: -If a seamount gets large enough to break the ocean surface, it becomes a volcanic island. Some seamounts are formed from magma rising at a divergent boundary, and as the plates move apart, the seamounts move with them, which can result in a seamount chain.

Detailed explanation-3: -What are Seamounts? Seamounts are underwater mountains that rise hundreds or thousands of feet from the seafloor. They are generally extinct volcanoes that, while active, created piles of lava that sometimes break the ocean surface.

Detailed explanation-4: -Volcanic islands occur in ocean basins (such as the Hawaiian Islands) or on or near ocean ridges (e.g., St. Paul Rocks and Ascension Island in the Atlantic Ocean) (Fig. 1.3). They are large volcanoes erupted on the seafloor whose tops have emerged above sea level.

Detailed explanation-5: -A new one just formed from an underwater volcanic eruption. The Pacific nation of Tonga is made up of 170 islands, but it just welcomed its newest addition-thanks to an underwater volcano. Near the center of the nation’s island formation lies the Home Reef volcano in the South Pacific.