why do so many of earth's volcanoes occur along plate boundaries?

Question

please answer this question and explain it.

Answer 1

There are three general classes of tectonic plate boundaries – convergent boundaries, divergent boundaries, and transform boundaries. Volcanism is typically associated with the first two of these three.

In the case of convergent plate boundaries, many of them involve the subduction of one plate beneath another (typically an oceanic plate beneath a continental plate, although, theoretically, any combination is possible). When one plate does subduct beneath another, minerals that melt at comparatively lower temperatures (like quartz, for example) within the rocks of the subducting plate will eventually begin to melt as the plate dives deeper into the mantle. These minerals, because they are typically lower in density, begin to buoyantly rise up as a liquid (i.e., magma) through the crust of the overriding plate. The magma will either collect in open spaces within the overriding plate, or eventually rise high enough to break the surface of the overriding plate in a volcanic eruption. The volcanism of the Andes Mountains of South America and the Cascade Range of the Northwestern United States are classic examples of volcanism resulting from convergent plate boundaries.

In the case of divergent plate boundaries, such as we find at mid-ocean ridges like the Mid-Atlantic Ridge, the tectonic plates are moving away from each other and, essentially, creating an open space between them. As this open space is created, the Earth’s mantle, which at mid-ocean ridges is already very near the surface, rises up to fill the now-open space created by the diverging plates. The reason why the mantle rises up in this fashion has to do with the way pressure affects the mantle's physical state (i.e., solid vs. liquid). As the pressure on the mantle is reduced as the plates move apart, the reduction in pressure tends to cause some of the minerals in the solid, rocky mantle to partially melt. *(In fact, significantly reducing the pressure on virtually any crystalline solid has the effect of making it easier to melt.) Much as we see in the example of subduction zones, this partially melted rock material rises buoyantly upward because of its lower density until it either collects in pockets within the diverging plates or is erupted at the surface.

The third class of plate boundaries – transform boundaries – are not typically associated with volcanism, although it certainly isn’t impossible, provided the transform boundary (in the form of a strike-slip fault) penetrates deep enough in the crust to reach the mantle.

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Answer 2

They all do. A volcano can't exist without a break in the earth's crust that allows the magna to come to the surface. Those only occur at the plate edges.

Answer 3

When plates move against each other that creates friction. Where there is friction there is heat. Plates are very very big and create lots of friction when the rub against each other, and that means lots of heat. Enough to melt rock! When that melted rock along the plate boundaries (called magma) comes to the surface, we call that a volcano.

Answer 4

The plate boundries were created by the volcanoes.

Answer 5

BECAUSE THE CORE OF THE EARTH IS MOLTEN LAVA AND ITS EASIER FOR THEM TO FORM THERE


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