Keeping Eyes on the Caldera: When Will Yellowstone Erupt?

The Yellowstone volcano in Wyoming is a geological marvel that has many scientists wondering when it might erupt. The lake in its southeast sector may seem calm, but an immense reservoir of molten rock is stored underneath. While it’s been 640,000 years since its last eruption, Yellowstone remains a topic of fascination. Could it erupt again? If so, when and what would happen?

The Yellowstone Caldera: Its Formation and History

A careful study of the volcano’s past gives insight into its future. It has experienced three massive eruptions — the first one occurred 2.1 million years ago, the second 800,000 years later, and the latest happened about 640,000 years ago. These events led to the formation of a caldera, a land depression caused when a volcano collapses on itself after an eruption. 
The first eruption created the Big Bend Caldera, while 1.3 million years ago, the second blast formed Henry Fork’s Caldera. The Yellowstone Caldera is the youngest yet largest of them all.

Current Activity and Monitoring Efforts

Yellowstone is considered a supervolcano, able to eject 1,000 cubic kilometers of tephra and capable of a magnitude 8 eruption, which raises curiosity about its next release of fury. Today, the volcano’s activities are closely monitored by a team of scientists from the Yellowstone Volcano Observatory (YVO), a collaboration between the U.S. Geological Survey (USGS) and nine state and federal agencies.

Frequent Earthquakes

Latest reports show that the volcano had 242 quakes in 2024, with the highest magnitude only reaching 3.3. This makes it among the most seismically active areas in the U.S. However, most of these earthquakes are too small to be felt.

Copious Heat

Geysers and hot springs are usually found where volcanic activity is present. However, with the Yellowstone caldera in an overabundance of these geological formations, researchers look at resurgent magma domes to monitor the supervolcano’s heat activity.

Scientists have identified two resurgent magma domes within the caldera. One is located north of Yellowstone Lake, while the other lies west, near some of the park’s most iconic features, including the Old Faithful Geyser.
These domes form when highly viscous, silica-rich magma pushes up to the surface, causing it to swell and bulge without erupting. The magma is too thick to spread into a full-blown lava flow. Most volcanic domes are small and without a crater.

The Lift and Subside of the Caldera Floor

The two identified resurgent domes formed when the ground lifted as magma filled the underground. Conversely, as the magma cools and begins to solidify, the ground subsides — this process has been closely monitored for over a century.

Volcanologists have studied these ground activities since 1923, with significant changes in recent decades. The caldera floor experienced uplift from 2004-2009 and 2014-2015.

Yellowstone’s 2-million-year history, combined with its ongoing geothermal activity, underscores the persistence of active magmatic processes beneath the surface. It’s also a reminder of the immense geological force that’s simmering.

Potential Eruption Scenarios

The slow and steady rise has led many scientists to question whether the supervolcano might erupt anytime in the foreseeable future. If it does, the intensity remains a significant concern. Yellowstone’s geological history suggests various scenarios, ranging from minor hydrothermal explosions to massive supereruptions, are possible.

Past eruptions provide a window into what might lie ahead. Out of three, two of its eruptions are considered to be among the world’s most colossal volcanic events. The last Yellowstone supereruption 640,000 years ago was over 1,000 times more powerful than the 1980 eruption of Mount St. Helens — a devastating event that killed 57 people, destroyed vast areas of Washington and Oregon, and sent ash clouds circling the globe for 15 days. 

Yellowstone’s supereruption sent immense plumes of scorching ash, molten rock, and toxic gases thousands of meters into the atmosphere. Pyroclastic flow swept across the region, leveling trees and obliterating landscapes. One-third of the North American continent may have been shrouded in darkness, with ecosystems affected for hundreds of kilometers. Today, evidence of its dramatic eruption is preserved in the 30-mile wide, 70-mile long Yellowstone caldera itself. Layers of thick volcanic debris can still be seen and are referred to as Lava Creek Tuff.

Despite a tumultuous history, scientists continue to emphasize that the likelihood of a catastrophic “doomsday” scenario is implausible.

The Challenges of Prediction

While scientists can use various methods to monitor volcanic activity, predicting volcanic eruptions is inherently complex. The challenges grow exponentially when it comes to Yellowstone. One major obstacle is deriving meaningful recurrence intervals from the limited data available. With only three major eruptions in the supervolcano’s history, there isn’t enough information to draw statistically valid conclusions about the timing of possible future eruptions.

If the average is drawn between the intervals of these events, which are 0.8 million and 0.66 million years, it results in an approximate recurrence interval of 730,000 years. This estimate suggests that the world is still about 90,000 years away from what might be considered an expected time frame for the next supereruption.

Despite this calculation, volcanologists caution against relying too much on these estimates. Yellowstone’s volcanic history, while significant, does not guarantee that its eruptions follow a predictable pattern. Volcanic activities are influenced by a multitude of factors, such as magma viscosity, tectonic activity, and changes in the Earth’s crust. These make it difficult to identify when or even if another caldera-forming eruption might occur.

Additionally, the vast magma reservoir does not necessarily indicate imminent eruption. Many volcanic systems contain molten rock for thousands of years without erupting.  

Impact on the Environment and Humanity

The Yellowstone Caldera has profoundly impacted the environment and humanity throughout its history. It continues to shape the region in various ways — from its catastrophic past eruptions to its current status as a preserved natural curiosity.

Historical Impact

Each supervolcano’s eruption has altered the surrounding landscape, creating enormous calderas and spewing ash and gases into the atmosphere. The most recent blast deposited thick layers of volcanic ash covering the entirety of North America. Such events would have devastated early ecosystems, leading to countless species’ migration, if not extinction.

Potential Future Impact

If Yellowstone were to erupt again, the consequences would be catastrophic on a global scale. Wyoming, Idaho, and Montana would be covered by hot avalanches of pyroclastic flow moving at 300 kilometers per hour and traveling for more than 100 kilometers. Ashfall could bury cities, contaminate water sources, and damage critical infrastructure over thousands of kilometers.

Additionally, it could disrupt the global climate pattern. The injection of volcanic gases like sulfur dioxide into the air could bring about a “volcanic winter,” lowering temperatures and affecting agriculture worldwide. These cascading effects would challenge modern humanity’s ability to respond, creating crises in public health, food security, and economic stability. While the probability of such an event happening within this lifetime is low, its potential impacts make it a key focus for researchers and disaster preparedness industries.

Staying Vigilant as the Supervolcano Sleeps

The ongoing research and monitoring efforts at Yellowstone Caldera go beyond mere prediction. Its catastrophic history leaves a legacy that allows scientists to understand Earth’s geologic processes. Its supereruptions illuminate the fascinating, complex forces beneath the Earth’s surface. It also provides a glimpse into the disastrous future should the volcano erupt. Though the supervolcano slumbers for now, the need for vigilance remains constant.