Unlocking Nature’s Secrets: Why Yellowstone’s Volcano Sleeps Untroubled

There’s no indication of an upcoming eruption at Yellowstone.

You might question why this is the case, given its tumultuous history: Yellowstone has experienced “supereruptions” — the most violent form of volcanic explosions that would have a regional impact, covering a vast area of the U.S. in ash. These eruptions were significantly larger than any recorded in history. (The most recent eruption, although not “super,” took place approximately 70,000 years ago, engulfing what is now the national park in lava.)

Recent studies shed light on why the well-known thermally active park, which features over 500 geothermal geysers, displays no indications of a potential eruption. Currently, the magma reservoirs (liquid rock) beneath Yellowstone have relatively low concentrations of this magma. They simply lack sufficient volcanic material to generate the conditions necessary for an eruption.

“We can definitively state that these regions could not initiate an eruption currently,” Ninfa Bennington, a research geophysicist from the U.S. Geological Survey who headed the study recently published in Nature, informed Mashable.

Multiple reservoirs, or pods, of magma exist beneath the Yellowstone Caldera, which is the expansive depression formed during a colossal eruption and subsequent collapse approximately 631,000 years ago. You can visualize each reservoir as a sponge, filled with tiny openings. There is some magma in these pore spaces, but it is far from saturated.

In the future, these sponges might become fully saturated with magma, reaching a crucial threshold — resulting in immense pressure accumulating underground, thus triggering an eruption. However, at present, there is no imminent explosive danger.

“We are quite far removed from that at this moment,” Bennington remarked.

Modeled ashfall from a Yellowstone supereruption.
Credit: USGS / Mastin et al.

The most devastating type of eruptions at Yellowstone, which create vast depressions known as calderas, are notably the least frequent.
Credit: USGS

To understand what is occurring in these essential magma reservoirs today, geologists employed a method referred to as magnetotellurics. Unlike radar or sonar, scientists do not generate or transmit signals to reveal what lies above or below. Instead, these assessments utilize the naturally occurring currents produced by Earth’s electromagnetic field. Because of its composition, magma is highly efficient at conducting electricity, thus providing insights into its presence deep beneath the Earth’s surface.

“It might take a very long time.”

The assessments, in addition to demonstrating Yellowstone’s inability to generate an eruption currently, indicated that the most primitive magma rising from Earth’s mantle to Yellowstone is directly linked to a reservoir in the northeast part of Yellowstone Caldera. This implies that this northeastern section could become the future hub of volcanic activity in Yellowstone.

Nevertheless, there is no indication that these reservoirs are accumulating magma. “It could be quite some time,” Bennington stated.

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If magma were to again find its way from deep within the Earth and saturate these shallower reservoirs, an eruption would not be unexpected. We would have many years, if not centuries, of forewarning. The migrating magma would provoke swarms of significant earthquakes, and the earth’s surface would undergo substantial deformation.

“These parameters are closely monitored, so ample warning will be provided of any future potential eruption,” the U.S. Geological Survey states.

At present, Yellowstone continues to be a location of minimal volcanic hazard. Indeed, there are occasionally minor eruptions driven by heated water and steam. Yet, it primarily consists of thermal pools and magnificent geysers, serving as reminders of what may eventually awaken, one day far off.