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Most volcanoes occur where tectonic plates meet. But scattered around the world are about 30 mysterious volcanic regions called hotspots, many of which are far from a plate’s edge.
Hotspots pose a puzzle for geologists. Is hot magma rising from deep within Earth’s mantle, or closer to the surface? Either way, pressure can build up, and a hotspot can erupt just like any volcano.
Hotspots and Island Chains
The Hawaiian Islands were formed by a hotspot. The Pacific plate moves over it, but the hotspot stays in place (or moves more slowly). When magma erupts, an island forms. Hotspots are long-lived, so over time, a series of long-lasting eruptions can form an island “chain.”
The hotspot that created the Yellowstone volcano works in the same way. A series of eruptions over millions of years has left a “chain” of calderas across the American west.
 Clues to Life’s Origins?
The rainbow-colored rings around Yellowstone’s scalding hot springs are colonies of tiny bacteria. They may offer us a glimpse of our own origins.
Clustered around mineral-rich volcanic vents deep on the ocean floor, bacteria much like these, which thrive in extreme heat, may have been the very first life forms on Earth. If so, every living thing on the planet owes its existence to them.
Volcanoes also produce the atmospheric gases that make our planet unique among all the planets we know: it can sustain life. Volcanoes can be destructive to human society. But in more ways than one, they are necessary for human existence.
Continue to Living with Volcanoes. >>
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