When huge volcanoes erupt, sending ash miles into the atmosphere and shutting down air travel for entire continents, the world can't help but take notice.
Yet everyday, around the planet, smaller displays of geothermal force take place. Sometimes, it's fairly static, like a gently simmering hot spring, and other times it's explosive—albeit less so than Iceland's Eyjafjallajökull.
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Strokkur Geyser, Iceland. Photo credit: Wikimedia Commons