These are the key points regarding the formation of volcanoes along tectonic plate boundaries and hotspot volcanism.
Majority of Volcanoes:
Most volcanoes on Earth are formed along the boundaries of tectonic plates. These plates are large pieces of the Earth’s lithosphere that are in constant motion, interacting with one another.
When tectonic plates collide, one plate can be forced beneath another in a process called subduction. As the descending plate sinks deep into the Earth, it experiences increasing temperatures and pressures, causing the release of water from the rocks.
The water released from the rocks in the subduction zone slightly lowers the melting point of the overlying rock. This reduction in melting point leads to the formation of magma, which can eventually rise to the surface and give rise to volcanic activity.
Spark of Life:
The release of magma from the subduction zone can reawaken a dormant volcano, providing the necessary “spark of life” for its eruption.
Not all volcanoes are formed due to subduction. Another mechanism is hotspot volcanism. In this case, a hotspot—a region of intense magmatic activity—exists in the middle of a tectonic plate.
Pushing Up through Crust:
The hotspot pushes up through the Earth’s crust, forming a volcano. While the hotspot itself is believed to be relatively stationary, the tectonic plates continue their slow movement, resulting in the formation of a volcanic chain or a series of islands on the Earth’s surface.
Hawaii Volcanic Chain:
The volcanic chain in Hawaii is often attributed to hotspot volcanism. As the Pacific Plate moves over the Hawaiian hotspot, a string of volcanoes has been formed, with each island representing a different stage in the volcanic activity.
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