Early signs of supervolcano activity below the Pacific Ocean

The Telegraph : Well below Earth’s crust, two structures, or “piles,” in the mantle are shifting and crashing into each other. The result is a well of partially molten rock the size of Florida that could lead to a massive supervolcano eruption sometime in the next 100 million to 200 million years. The two piles were first discovered in the 1990s by scientists examining data from 51 major earthquakes and determining how the seismic waves varied as they passed through the mantle. The piles themselves appear to be solid rock areas bounded by semi-molten rock and sitting on top of Earth’s core, much the way the continents sit on the mantle. Michael Thorne of the University of Utah and his team used x rays to generate images of that area of the mantle. They determined that the two piles are actually colliding, pushed around by the mantle’s internal convection and subduction. Thorne and colleagues say the collision is likely to result in one of two types of eruption. The first is a hotspot plume similar to the Yellowstone eruptions that covered much of North America in ash over the past 2 million years. The second is a flood basalt eruption that could bury a large area in lava.