It's no secret that Earth's volcanoes are the result of magma rising through the planet's mantle, but have you wondered just where those 'roots' run? UC Berkeley can provide an answer. It just created the first-ever detailed 3D map of the Earth's interior by studying the path of seismic waves. The model shows mantle plumes (where the hot rock flows) starting at the bottom of the core-to-mantle boundary and climbing to the top, where they connect to volcanic hotspots in the Earth's crust. As it turns out, the plumes don't take a straight path -- they often spread out as they merge with the colder upper mantle. It's also clear that most of the world's volcanoes (such as those in the Pacific's island chains) ultimately come from two large "blobs" of hot rock at the core boundary.
The model isn't perfect. It didn't link plumes to some volcanoes, such as the one at Yellowstone National Park. However, it's good enough to represent the first hard evidence of magma plumes, and there are promises of higher-resolution maps in the future thanks to gravity-sensing satellites. While it's doubtful that scientists will ever know as much about Earth's insides as they do about the top layer, this below-ground region is no longer as mysterious as it once was.
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