Friday, February 28, 2014

A Magnitude 22.0 Earthquake?? A Star Wars Analogy

A couple of months ago (on Christmas actually, Merry Christmas Geologists!) the USGS, which releases customized Earthquake Notifications based on a users settings, released the news that a magnitude 22.0 earthquake just struck Montana (pictured below).


Now this was clearly a typo. It was meant to be 2.2, however, it does bring up an interesting conversation.(You can see the updated page HERE). What is a Magnitude 22 earthquake capable of?. Some of the comments on my Facebook post included (names abbreviated to protect their identities, if you want your name un-abbreviated, let me know):

Steve R: Looks like NBC now has the plot for the completion of it's earthquake trilogy. First it was "10.5"...then "10.5 Apocalypse"...now" Montana 22.0 the day the Earth went boom"...all staring Beau Bridges as Beau Bridges acting like an authority figure. 
Tyler S.: It wasn't flattened, there's a new 6 km high fault scarp. 
Thomas H.: Mag 22.0? Impressive! The Chicxulub Impact should have produced only a 10.8! 
Thomas H.: A 22.0 should have toppled every building on the planet, and probably caused mountains all over the world to collapse into piles of rubble. At least. 
Monica S.: Just as a reference, a Mw 10.0 would have a rupture length roughly equal to 1/4 of the planet's circumference. That is why a 10.0 could physically never happen. A 10.5 would rupture around the Earth 1.5 times. (If that movie 10.5 were real, Earth would have been obliterated). This is assuming a max rupture depth of 30 km. Mw 22 is 316,227,766,016 times more powerful than a 10.5.

To understand the audacity of a Magnitude 22.0 earthquake, lets give some earthquake basics. The measure of an earthquake's magnitude is essentially equivalent to the energy released during the initial rupture of the fault (I know they are not exactly the same, but it is close enough). Identification of earthquakes often start with a Magnitude 2.0 and go up to a Magnitude 10, with the largest recorded earthquake in history being a Magnitude 9.5.



The magnitude scale specifically measures the amplitude of the of the waves released from an earthquake (USGS). The Moment Magnitude scale, as it is called (replaced the Richter Scale), is a logarithmic scale. As it goes up one number the size of the amplitude increased by a factor of 10. To make it a little easier to understand you can compare this to the energy released. So, each whole number is 31.62232 times more powerful than the last one (i.e. a magnitude 3 is 31.622 times more powerful than a magnitude 2).

For energy comparisons, let us convert the amount of energy to Joules that is released from an earthquake. The largest earthquake ever recorded was the Chilean 9.5. That would have released 1.12 x 10^19 joules of energy. The Hiroshima nuclear bomb released 6.3 x 10^13 joules of energy by comparison (Wikipedia), quite a bit less than a 9.5 earthquake. Now a magnitude 22 earthquake is 12.5 degrees of magnitude larger than a 9.5. So calculating it would mean that it would be 31.662^12.5 more powerful than a 9.5 (5.7 x 10^18 times more powerful). This equates to 6.31 x 10^37 joules of energy (calculated here: http://www.convertalot.com/earthquake_power__calculator.html).

There is a limit to the size of an Earthquake based on the physical properties of rocks, but let us just ignore that for now.

The energy released in a Magnitude 22 earthquake is a lot of energy, but it is a little hard to grasp numbers that big. A magnitude 3.5 earthquake, which is on the limit of being felt by most people, releases 1.12 x 10^10 joules of energy. On the other hand it has been estimated that the power required by the Death Star in Star Wars (yes I'm going there) to destroy a Earth sized planet was 2.2 x 10^32 joules of energy (as mentioned HERE and elsewhere).




So the amount of energy required to destroy a planet (2.2 x 10^32 joules) is actually equal to an earthquake with a magnitude of 18.33, much smaller than the Magnitude 22 (6.31 x 10^37 joules) earthquake reported. Although the 2.2 x 10^32 joules is a bottom estimate, it is possible that the Death Star could create much more energy than that, just to make sure the planet was obliterated.

Therefore, I believe I have proof to indicate that the Earth was struck by a Death Star laser on Christmas, 2013. But somehow, we survived, and now they are trying to cover it up. Perhaps this was a test of the Death Star that the government supposedly wasn't building (The White House).

Some other numbers courtesy of Dinogami:
  1. Manicouagan impact = 1 x 10^21 joules
  2. K-T  (K-Pg) Chicxulub impact = 4.2 x 10^23 joules
  3. Sun puts out 3.8 x 10^26 joules (however that is all over, not concentrated)
  4. Impact of a Mars size body on the Earth = 4.5 x 10^31 joules 
It appears that our Magnitude 22 earthquake was one of the largest events to happen to the solar system since the last supernova.

5 comments:

  1. By ways of comparison, the Manicouagan impact released about 1 x 10^21 J, the terminal-Cretaceous Chicxulub impact is estimated to have released 4.2 x 10^23 J, and the Sun puts out 3.8 x 10^26 J/s (though, of course, much less hits the Earth). The impact of a Mars-sized body with the Earth, such as has been theorized to have produced the Moon, would have released something like 4.5 x 10^31 J, pretty close to the planet-destroying limit!

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    1. Oooh. Good numbers :-) I will have to add those to the post.

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    2. A student in class once asked me what the largest possible earthquake would be. I assumed a fault plane that consisted of a full earth cross-section, and an offset of 1 earth diameter. I assumed a shear strength equivalent to near-surface crustal rocks, which I recognize is WAY off, and I got a moment magnitude of ~15.3. From splitting the earth into two equal hemispheres.

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    3. Only a 15.3? Pishaw. You obviously need a Death Star to up your game.

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  2. Awesome point of view! Haha definitely a government death star test.

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