Yellowstone's Second Magma Reservoir: 2015 Discovery

Yellowstone's Hidden Fire

Yellowstone National Park, America’s most visited, conceals a massive magma system larger than previously mapped. Scientists had long known about an upper magma reservoir three to nine miles below the surface. The seismic imaging picked up partially molten rock in a vast chamber stretching fifty-five miles long and twenty miles wide. Since 2015, the university of Utah researchers have revealed another reservoir, deeper and considerably larger — nearly 4.5 times the volume of the upper magma chamber. Coupled, the reservoirs feed the park’s volcanic systems via a mantle plume from the Earth's depths.

A Different View, Farther Down

Where warm magma creeps to just beneath the earth's crust, the lower magma reservoir is unique. 4.5 times larger than the upper reservoir, it stretches out 12-28 miles deep. That means it's nearly 200 miles below the park’s surface. Far greater volume of partially molten rock means this reservoir wouldn’t just be bigger, but more influential to the park’s geology. And this is only the beginning, as the reservoir's edges remain uncharted.

Dangerous Heat, Slow Flow

People may imagine a supervolcano like a red-hot coal ready to burst. In reality, Yellowstone’s magma chambers are slow-moving and cool. This mantle plume is a solid, flowing rock that rises from the Earth’s core. It reaches the lower magma reservoir, heating it. The heated reservoirs slowly melt the surrounding rocks, forming more molten rock. The magma is too molten to erupt directly. Instead, it forms regular geothermal activity like the famous geysers. The USGS tracks the temperature and movement of this magma. When the USGS reports a surge, that may signal imminent activity.

Constant Monitoring, Minimal Risk

The USGS currently does not see the signs of increased activity. Heat levels, swarm tremors, and ground water levels all remain stable. Hence, the risk of a supereruption is low — 0.00014% for any given year. A Yellowstone eruption may seem frightening. But unless the USGS alerts the public, the park’s infrastructure can withstand typical magma activity.