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Roger Weller, geology instructor

by Robert Posey
Historical Geology
Spring 2010


The Yellowstone Caldera:
Why We Won’t Die Terribly From an Eruption

     All over the world there are hundreds of things that can cause damage on the global scale. Some of these things include meteorite impact, nuclear weapons, bioengineered viruses which could kill billions, and super volcanoes. The Yellowstone super volcano in particular is extremely dangerous. If it erupted the Yellowstone Caldera could kill billions of people, perhaps the entire population of the world. However, due to the mathematical principle of the Law of Averages as well as a lack of severe current geologic activity we do not need to worry about  the Yellowstone Caldera erupting for at least another 1.57 million years.

Why we do not need to worry about an Eruption

            The first reason we do not need to worry about the Yellowstone Caldera erupting is because of the Second Law of Averages. This law states that a sample’s average will be approximately related to its expected outcome. And example being that if you flip any given coin 100 times and receive X amount of heads and then flip it another 100 times you should receive a number of heads approximately equal to X. Therefore when you take the number of eruptions and the time between each eruption and then find the average, the next eruption will occur approximately at a similar time after the most recent eruption. Then if you take how long ago the last eruption was and subtract it from the average time in between eruptions you will receive a fairly accurate time estimate as to when the next eruption will take place. The following table will show my calculations leading to the 1.57 million year estimate. This table also shows dates of the eruptions, the times between eruptions and the average time between the eruptions. Please note there is a margin of error for plus or minus 0.07 million years and P stands for present day. Numbers are from the Official Yellowstone National Park Website.



Eruption dates in Million years ago

Time between eruptions in millions of years ago


























Average time between eruptions

2.1 Million Years



            Another reason people should not worry is that there is a lack of major geologic activity in the area surrounding the caldera. The largest recent earthquake according to the US Geologic Survey is a mere 3.0 (“Magnitude 3.0”); not nearly enough to cause a breach of the magma pocket under the crust triggering an eruption.  It would require an earthquake of at least a 7.0 or higher directly above, next to or below the magma pocket to cause a breach allowing pressure to escape and causing an eruption according to the process described in the Figure following this paragraph.

cauldera eurption process part 1.bmp






cauldera eurption process part 1.bmp


1.       Magma Pocket Forms
       Magma escapes to surface releasing pressure
       As the pressure is released crust rapidly drops cracking
       As crust cracks more pressure escapes launching the cracked and damaged surface into the air
       Magma, rock and ash are released
       Caldera cools and magma solidifies
       Caldera begins to erode and fills with water
       Caldera erodes further and becomes a lake-like structure filling with water and vegetation 


Reasons people might fear an eruption of the Yellowstone Caldera

            There are many reasons to fear an eruption of the Yellowstone Super volcano. These reasons include the scale of the eruption, the location of the eruption, and the effects of the eruption. Although these might be good points they pale to the fact that we still have at least another 1.5 million years before the next eruption. Also, even if it was discovered the volcano was going to erupt 3 years before it actually happens we would be powerless to stop it or even completely evacuate the blast zone. So we shouldn’t worry about what we cannot control.

            Another counter argument that many people like to point toward is Mount Saint Helens and how geologists failed to predict when it would erupt. However, because we studied that particular eruption we now have a great deal more knowledge about volcanoes and can now predict eruptions with a great deal more accuracy than before the Mount Saint Helens eruption.


Eruption Scale

When Mount Saint Helens erupted in 1980 it was about three times more powerful then the atomic bombs dropped on Japan during World War II. If The Yellowstone Caldera exploded it would be three times more powerful than Mount Saint Helens. That is three-thousand times more powerful then the atomic bombs which leveled entire cities during World War II. Again, however, even if we had advance warning there is very little we could do to stop the caldera or evacuate the area in the danger zone. Also, sense the eruption will not occur for another 1.5 million years so even your great-grand children will not have to worry about the eruption. (Weller)

 mt st helens and yellowstone compareson.jpg

Map by: United States Geological Survey


Eruption Location

          Other people are afraid because of the eruption’s location. Although it is possible for the eruption to occur in the same place as previous eruptions it is highly unlikely because no two eruptions have ever occurred in the same location. Instead there are two other locations which are possible. The first is to the North East of the current caldera, and the second lies to the North West. If the pattern holds, the eruption will occur to the north east. However, Professor Roger Weller of Cochise College believes the North Western location to be the most likely. The geologic evidence such as earthquakes, geysers and hot springs supports this theory as they are all located to the north west of the current caldera as you can see in the map following this section. (Weller; “Monitoring”)

circles of uplift.GIF


Local Eruption Effects

            If the Yellowstone Caldera was to erupt today according to my comparison of several accounts of both recent and historical disasters these are what the local effects of the eruption of the Caldera would be. (“Pinochet”; Clabugh and Wood 1-2; Olzam, Keskinocak, and Swann A. 13; Alan A.4; Hazzard A.26; Luhnow and Ianthe A.16; Marc A.6; Gautam A.14; Pelling and Pelling 21-37):

·         A total collapse of agriculture from California to the Mississippi
  Disruption of communication in the western United States
  Disruption of transportation in the western United States
  Denial of basic utilities all over the western United States
  Looting and general break down of civil order in the Western United States,
        most likely resulting in marshal law being enacted is most states west of the Mississippi

 Disruption of Air Traffic directly around the caldera immediately after eruption

            Although the local effects would be great, most people within the ash fall zone would survive and since Central California, which grows enough food to feed the entire United States and then some, would be largely unaffected most United States Citizens would not have to worry about starvation. Also, if people remain calm, the looting and civil disorder will be kept to a minimum. (However, it is recommend that if the Yellowstone Caldera were to erupt, that you clean your gun and stock up on ammunition to protect yourself until government peace keeping forces arrive.)


Global Eruption Effects

            If the Yellowstone Caldera were to erupt today according to a comparison of several accounts of both recent and historical disasters these are what the local effects of the eruption of the Yellowstone Caldera would be. (“Pinochet”; Clabugh and Wood 1-2; Olzam, Keskinocak, and Swann A. 13; Alan A.4; Hazzard A.26; Luhnow and Ianthe A.16; Marc A.6; Gautam A.14; Pelling and Pelling 21-37):

 Mass starvation in countries that primarily import their food from the United States.
 Disruption of air traffic on a world-wide scale due to the large volumes of volcanic ash that would choke jet engines.
 Nuclear winter which occurs when the ash or dust blocks out sunlight causing planetary temperatures to drop, which in turn would kill off most plants and  animals which feed off plants.

            Although these worst case scenarios are possible, they are unlikely. It would be difficult but not impossible for most countries which import their food from the United States to either find a new source of food to import or become self-sufficient. In fact, the only reason most countries import their food from the United States is because it is cheaper than growing it locally. If that source becomes unavailable it would become cheaper for countries to grow their own food. This means they have the available land, but they are just saving their pennies. Although some people would go hungry for a few years eventually food supply and demand would balance out.

            Although ash would affect global temperatures as well as sunlight levels plants have survived many previous and far more intense temperature drops in earth’s history. Also, through human techniques of genetic engineering and selective breeding human beings could create crops that would be able to thrive in colder temperatures and with less sunlight. Although many wild animals would become endangered or go extinct, humans could preserve some through the cold to repopulate after the ash has settled or humanity could leave animals to their own devices and allow natural selection to take place. Plants, which are remarkably resilient against mass extinction, would have no trouble repopulating after a disaster of the scale of The Yellowstone Caldera eruption. (Weller; Wincander and Monroe pg. 259)

Death totals

            Another reason people might fear an eruption from Yellowstone is the amount of death it would cause. After comparing a variety of sources to calculate a conservative estimate of the amount of people that would die both directly and indirectly from the eruption of the Yellowstone Caldera this total was reached. (“Pinochet”; Clabugh and Wood 1-2; Olzam, Keskinocak, and Swann A. 13; Alan A.4; Hazzard A.26; Luhnow and Ianthe A.16; Marc A.6; Gautam A.14; Pelling and Pelling 21-37)

       Deaths from immediately to six months after the disaster: one half million people

       Deaths from six months to a year after the disaster: one half billion people

       Deaths from one to five years after the disaster: 3 billion

       Total Deaths resulting from the disaster: 3.55 Billion people

            Once again the general population should not worry; there is no evidence of an eruption occurring anytime soon. Also, if Yellowstone did erupt there is nothing anyone can do to stop the eruption, so why worry about something a person can’t control. Instead people should spend their time worrying about things they can control. That way something might get done about things human beings have control over.

            The population in general does not need to worry about an eruption from the Yellowstone Caldera anytime soon. The reasons you should not worry far outweigh the reasons you might want to worry. The lack of geological activity necessary for an eruption to occur is a major reason. Another reason is that according the Second Law of Averages we have another 1.5 million years at least before another eruption. These are the reasons that people will not die a terrible death from the Yellowstone Caldera eruption.



Works Cited


"Magnitude 3.0 - YELLOWSTONE NATIONAL PARK, WYOMING." USGS (2010): Web. 8 Apr 2010.


Yellowstone National Park Official Website." (1999): n. pag. Web. 29 Mar 2010.

"Not Since Pinochet, Chile’s Army Back On The Streets." Morning Edition. NPR. Washington, D.C.: Mar 4,2011. (2010): 1-2. Print.

Clabugh, Rich, and Daniel B. Wood. "Chile earthquake: How California would fare." Christian Science Monitor. Boston, Mass.: March 1, 2010. (2010): 1-2. Print.

Ergun, Ozlem, Pinar Keskinocak, and Julie Swann. "Logistics ignored in disaster relief." Atlanta Journal 3 Feb. 2010: A. 13. Print.

Gomez, Alan. "Quake's victims' graves go unvisited for now; Survivors are busy just surviving." USA TODAY 11 Feb. 2010: A.4. Print.

Hazzard, Shirley. "In The Shadow of Vesuvius." New York Times 5 Oct. 1986, Late Edition (East Cost): A.26. Print.

Luhnow, David and Ianthe, Jeanne Dugan. "World News: Quake Tops List Of Costly Disasters."

Lacey, Marc. "Estimates of Quake Damage in Haiti Increase By Billions [Foreign Desk]." New

Naik, Gautam. "Chile Earthquake: Why Bigger Quake Caused Less Damage --- Scientists Say

Pelling, Marc, and Kathleen. "Disaster Politics: tipping points for change in the adaptations of sociopolitical regimes." Progress in Human Geography. (2010): 21-37. Print.

Weller, Roger. “On Volcanic or Igneous Rock.” Cochise College. Sierra Vista Campus. 23-28 Aug. 2009.


Weller, Roger. “On Mass Extinction.” Cochise College. Sierra Vista Campus. 15 April 2010.

Wincander, Reed, and Monroe S. James. Historical Geology: Evolution of Earth and Life through Time. Sixth Edition. Belmont, CA: Brooks/Cole, 2007. 259. Print.



Webpage’s on Yellowstone

1.  The official website of Yellowstone National Park    The Official National Park Service Website  For weather at Yellowstone
            These people are just crazy, but have a good, if a bit light, summery of the Yellowstone Caldera. Also, they have other far more likely doomsday events, but mostly they are just crazy.
            This web page relays real time still images of the Old Faithful Geyser