The amount of energy produced during an earthquake and the amount of energy produced during a nuclear explosion are very different. An earthquake produces energy through the shifting of tectonic plates, where as a nuclear explosion produces energy through atomic fission or fusion.
There are nine levels of earthquakes, with level one being the weakest and level nine being the strongest. The strongest recorded earthquake has a magnitude of 9. This means that the total energy released in the earthquake is 9 units of magnitude higher than the earth’s base or foundation, which is called the hypocenter.
Unlike earthquakes, there is only one level of nuclear explosions: extremely powerful. The worst nuclear explosion would be a category 7, which would have an equivalent magnitude of 10. An atomic bomb would be a category 5, which has an equivalent magnitude of 9.5.
Comparable masses
When comparing the energy of a nuclear bomb to that of an earthquake, experts compare the masses of the bombs instead of their yields. This is because masses are universal values, and yield is specific to nuclear explosions.
Yield is the amount of energy released in a nuclear explosion. It is usually expressed as tons of TNT equivalent, which takes into account the mass of the bomb material and the strength of the explosion.
Since earthquakes are a natural phenomenon, they have their own inherent energy. The same earthquake magnitude scale used to measure earthquakes’ strength measures their inherent energy.
Theoretically, any two earthquakes with the same magnitude would have the same amount of inherent energy. However, it depends on where the earthquake occurs how much external energy is transferred to it. It may thus have more or less total energy than expected based on its magnitude.
Comparable energies
While the energy of a nuclear bomb is incomparable to that released by an earthquake, it is possible to compare the two.
According to the IAEA, the average energy released during an earthquake is around 0.1 megatons of TNT-equivalent energy. A megaton of TNT-equivalent is 1015 units, or a million times greater than a ton of TNT.
So, on average, an earthquake releases about 1/100th the energy of a 1-megaton hydrogen bomb. However, earthquakes can be much stronger or weaker than this average value. Some can even rival the energy released by a nuclear bomb!
Earthquakes and nuclear bombs both have the potential to cause significant damage depending on their strength.
Rupture distance
When an earthquake occurs, the distance that the ground ruptures can be another important indicator of its power. If the rupture is very long, then the earthquake was likely more powerful.
This is because earthquakes of similar magnitude can have different rupture lengths. Magnitude is a measure of an earthquake’s size, or how much the earth moves during the event.
Earthquakes with a higher magnitude have deeper fault breaks, which means more total distance that the earth moves and shakes.
Since magnitude is a ratio, an earthquake of any size could have a high magnitude if its ratio is high. For example, an earthquake that measures 8 on the Richter scale has a higher magnitude than one that measures 7, but only by one break in the earth’s surface.
Explosive yield
In terms of explosive yield, a 1-megaton hydrogen bomb is about 75 times more powerful than the 9-megaton weapon dropped on November 1, 1952 on the Eniwetok Atoll in the Marshall Islands.
By comparison, a major earthquake can release far more energy. The magnitude 9.0 earthquake that triggered the devastating tsunami in Japan in 2011 released as much energy as about 200 million tons of TNT explosives.
In other words, an average earthquake releases as much energy as 200 million 1-megaton hydrogen bombs! That’s why it is so important to be prepared for earthquakes — they can be far more deadly and destructive than even the most powerful of nuclear weapons.
The only downside to an earthquake is that you can’t direct its force — it affects an entire area indiscriminately, whereas a nuclear weapon can be aimed at a specific target.
Underground detonation
Although most nuclear tests have been above-ground detonations, there are many reasons that underground detonations are performed.
Underground detonations can reduce the amount of radioactive fallout produced by the test. If the intention is to test the underground strength of a country, then an underground detonation is smart because it will not harm its population or infrastructure.
The energy produced by an underground nuclear test is almost identical to that of an above-ground nuclear test. The difference lies in how the earth reacts to the shock wave caused by the bomb.
Dr. Bruce Truman, director of the Institute for Radiological Protection and Nuclear Safety, explains: “The rock in which it’s buried will attenuate some of those waves … so you don’t get such a strong response on the seismometers, but in general it will be equivalent.
Surface detonation
A nuclear weapon can be detonated at the surface, called a surface detonation. This can be in the form of a bomb dropped from an aircraft or missile, or it can be planted underground and triggered to explode at the surface.
These types of explosions can have greater damage than subsurface detonations. The earth and material above the bomb are vaporized, creating a crater.
Damage depends on the size and type of bomb, how far it is buried below ground, and how large an area it is exposed to.
Surface detonations are very efficient ways of damaging structures on the ground. They cause secondary effects such as fires and collapsing buildings that contribute to more overall damage.
The difference isn’t as great as you think
When most people think about an earthquake, they think about the ground shaking. While this is certainly a significant part of an earthquake, it is not the only part.
In fact, the shaking of the ground is only one of three parts that make up an earthquake. The other two parts are vibration and displacement of the earth’s surfaces.
When an earthquake occurs, the earth’s solid surface undergoes a kind of deformation due to stress. This deformation can be imagined as if you pulled on the surface of water in a pool, or as if you shook the ground beneath your feet.
These two kinds of deformation occur simultaneously when there is an earthquake, which is why it is so difficult to keep your balance when one happens.
Size and frequency matter
Though we focus on the most powerful earthquakes, the size of the quake does not tell the whole story. The size tells you how much the ground moves, but not how much energy is released.
In fact, there are earthquakes that release more energy than some magnitude 9s! This is because magnitude 9 quakes occur quite frequently, so there’s a higher chance that one will release more energy than a lower magnitude earthquake that occurs less frequently.
There are also lower intensity earthquakes called tremor events. These can happen very frequently, and together they can release more energy than a single magnitude 9 earthquake.
Tremor events are hard to detect, which is why we don’t pay much attention to them. But since they occur so often, they can add up to a lot of energy released.
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