What states would be destroyed if Yellowstone erupts?

If Yellowstone's supervolcano were to experience a catastrophic eruption, the immediate and long-term effects would be devastating for not only the United States but for the entire world. Such an event, while incredibly rare, has the potential to wreak havoc on vast areas of the United States, particularly the western part of the country, and could cause significant climate disruptions on a global scale. The extent of the damage would depend on the size of the eruption, but based on the volcanic history of Yellowstone and scientific models, we can estimate the impact on surrounding states and beyond.

The Supervolcano and its History

Yellowstone National Park, primarily located in Wyoming, sits atop one of the world's largest active volcanic systems. The Yellowstone caldera, a supervolcano, has erupted three times in the last 2.1 million years: 2.1 million years ago, 1.3 million years ago, and 640,000 years ago. Each of these eruptions released massive amounts of volcanic material, creating widespread devastation.

The most recent super-eruption produced approximately 240 cubic miles of volcanic material, forming the current caldera and blanketing much of North America with ash. The potential for future eruptions is a matter of concern, though scientists believe the likelihood of a super-eruption occurring in the near future is low.

Immediate Impact of an Eruption

If Yellowstone were to erupt at a supervolcano level, the initial impact would obliterate everything within a radius of approximately 50 to 100 miles from the eruption site. This would include parts of Wyoming, Montana, and Idaho. The explosion would release a vast amount of ash, pumice, and lava into the atmosphere, creating pyroclastic flows that would incinerate vast areas.

States Directly Affected by Pyroclastic Flows:

1. Wyoming: As Yellowstone is located in Wyoming, the state would bear the brunt of the eruption. The area immediately surrounding the park would be decimated, with ashfall and pyroclastic flows causing widespread destruction. Major towns like Cody, Jackson, and the state capital Cheyenne could be severely impacted.

2. Montana: Southern Montana, particularly areas near Yellowstone like Bozeman, Billings, and parts of the Gallatin and Absaroka mountain ranges, would experience significant destruction due to ashfall and pyroclastic flows.

3. Idaho: Eastern Idaho, including cities like Idaho Falls and Pocatello, would be close enough to experience devastating impacts from pyroclastic flows and heavy ashfall.

The Spread of Volcanic Ash

The most far-reaching effect of a Yellowstone eruption would be the ashfall. The eruption would inject a massive cloud of volcanic ash and gases into the stratosphere, which could travel thousands of miles across the country, depending on wind patterns. Volcanic ash is highly abrasive and can be fatal to living organisms if inhaled in large quantities. It also disrupts electrical equipment, clogs engines, and can collapse roofs under its weight.

States Severely Affected by Ashfall:

1. Utah: Salt Lake City and much of Utah would likely be covered in thick ashfall. This would disrupt daily life, destroy agriculture, and make breathing outdoors dangerous without proper filtration.

2. Colorado: Denver and other parts of Colorado would experience heavy ashfall, leading to major disruptions in transportation, water supplies, and power.

3. Nevada: Las Vegas and the surrounding regions could also be impacted by significant ashfall, particularly in the eastern part of the state.

4. South Dakota: The eastern spread of ash would reach as far as South Dakota, potentially affecting cities like Rapid City and areas closer to Wyoming.

5. Nebraska: Central and western Nebraska would experience significant ashfall, potentially leading to hazardous conditions for agriculture, transportation, and daily life.

States Moderately Affected by Ashfall:

1. North Dakota: Although North Dakota is farther away from Yellowstone, it could still experience moderate ashfall that would affect the environment and infrastructure.

2. Kansas and Oklahoma: These states would likely see lighter ashfall, but it would still be enough to cause serious air quality problems and disrupt transportation.

3. Minnesota and Iowa: While the ashfall here would be less severe than in the states closer to Yellowstone, it could still pose health risks and disrupt agriculture and daily life.

States Most at Risk of Destruction or Severe Impact

State	Level of Impact	Nature of Damage
Wyoming	Catastrophic	Ground zero, total devastation
Montana	Severe	Heavy ashfall, infrastructure collapse
Idaho	Severe	Ashfall, loss of agriculture and power
Utah	Major	Air quality issues, infrastructure disruption
Colorado	Major	Ashfall, economic and transportation impacts
Nebraska	Moderate to Severe	Agricultural loss, infrastructure disruption
North/South Dakota	Moderate	Ash contamination, health and climate effects
Other Midwest & East	Light to Moderate	Ashfall, economic effects, climate change

Nationwide and Global Impact

The ash and gases released from the eruption could trigger a volcanic winter, with sulfur dioxide and other particles blocking sunlight and leading to a significant drop in global temperatures. This could last for months or even years, leading to widespread crop failures and famine. The disruption to the global climate would affect food production, particularly in regions dependent on stable weather patterns, such as the Midwest United States and parts of Europe and Asia.

Environmental and Economic Impacts:

1. Agriculture: The ashfall would destroy crops across vast swaths of the United States, leading to food shortages and skyrocketing prices. Livestock would also be affected, with grazing lands covered in ash and water sources contaminated.

2. Air Travel: Volcanic ash is highly dangerous for aircraft, and air travel across North America would likely be grounded for weeks or even months following the eruption.

3. Economy: The economic fallout would be immense, with billions of dollars lost due to property damage, crop failure, and the shutdown of transportation networks. The global economy would suffer as supply chains are disrupted, and industries reliant on agriculture, transportation, and manufacturing face collapse.

4. Human Health: Respiratory issues would become widespread due to the inhalation of ash particles, particularly in the states closest to Yellowstone. Hospitals would be overwhelmed with cases of respiratory distress, and the healthcare infrastructure could be strained to its breaking point.

Global Consequences

The eruption of a supervolcano like Yellowstone would not just be a local or national catastrophe. The release of large amounts of sulfur dioxide and ash into the atmosphere could lead to a significant cooling of the Earth's climate, similar to what occurred during the eruption of Mount Tambora in 1815, which caused the "Year Without a Summer." Global temperatures could drop by several degrees, leading to widespread crop failures and potential famine across the world. The economic and social ramifications of such a climate shift would be profound.

Conclusion: A Regional Disaster with National Consequences

While the possibility of a super-eruption at Yellowstone is remote, the consequences of such an event would be catastrophic. The states of Wyoming, Montana, and Idaho would be immediately devastated by pyroclastic flows, while much of the western and central United States would suffer from severe ashfall. The economic, environmental, and social impacts would ripple across the country and the world, leading to global climate changes, agricultural collapse, and widespread economic disruption. 

The good news? Scientists say such an event is extremely rare and unlikely anytime soon. The Yellowstone supervolcano is carefully monitored, and there are no signs of an impending eruption.

Still, understanding the risks helps us prepare for the unexpected and appreciate the powerful natural forces that lie beneath America’s first national park.