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also have a very large summit crater, or series of craters following the line of a fissure. They are frequently filled with a pool of lava.
Seamounts
seamounts are submarine
volcanoes. They also comprise
107 of the world’s known active
volcanoes. Most seamounts
occur along the submarine ridges
that cross the great oceans. Most
of the seamounts that send explosive materials into the air rise out of relatively shallow seas. There are certainly many more active seamounts than this, but they rise from the deep ocean floor and erupt entirely under water, and so their eruptions are thus far unknown. Loihi in Hawaii is an example of a deep seamount that has now risen fairly close to the surface of the sea. Its summit crater is one kilometre below the surface. It is the youngest volcano of the Hawaiian chain and will probably rise to be as great as Mauna Loa. Hidden seamounts are mostly detected through the earthquake swarms that
(Above) Mount Rainier, Washington, is a stratovolcano, made of both lava and ash
layers. Notice that the sides of the cone have a concave slope. The volcano rises high above
the general level of the Cascade Range in the northwestern part of the United States. Because the volcano has not erupted for some time, the summit and flanks have been eroded by glaciers.
(Left) The summit crater of Kilauea, on Hawaii. Notice the many layers making up the walls
of the summit crater. Each one represents a separate major eruption.


































































































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