Pools of still water, rising steam and sudden geyser plumes make Yellowstone National Park resemble an open‑air spa complex. Geophysics tells a different story. Beneath the forests and boardwalks, a vast magma reservoir spreads across tens of kilometers, driving an intense heat flux that forces water to circulate, boil and erupt back into the air.Each hot spring, geyser and prismatic pool is a vis...More