Regardless of the specific mechanisms that lead to their formation—such as subduction of tectonic plates, hot spots, or divergent boundaries—all volcanoes share a common main process: the ascent of magma from the Earth's mantle to the surface.
This process involves several key steps:
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Magma Generation: Magma is formed in the mantle or lower crust due to conditions that decrease pressure or increase temperature, or the addition of volatiles (like water), which lowers the melting point of rocks.
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Magma Ascent: Once formed, the magma is less dense than the surrounding rock, causing it to rise through the crust. This ascent can occur through fractures, existing conduits, or by melting surrounding rock.
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Magma Accumulation: As magma rises, it may accumulate in magma chambers within the crust. Here, it can experience changes in composition and pressure, and allow for the crystallization of minerals.
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Eruption: If enough pressure builds in the magma chamber, or if the magma composition changes (leading to increased gas content), an eruption can occur, bringing magma (now termed lava) and gases to the Earth's surface.
Despite differences in eruption styles and formation processes, this fundamental cycle of magma generation, ascent, accumulation, and eruption is a commonality among all volcanoes.
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