1874: Geologic Faults

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Geologic Faults
I live on a torn-bag-of-potato-chips-where-the-tear-is-rapidly-growing fault, which is terrifying.
Title text: I live on a torn-bag-of-potato-chips-where-the-tear-is-rapidly-growing fault, which is terrifying.


This comic appears to be a successor to 1714: Volcano Types. Similar to its predecessor, the comic explores several phenomena (in this case, geologic faults), both real, and several made up for the point of a joke.

A fault is a geologic feature involving a planar fracture with displacement in a large mass of rock, including the boundaries of two tectonic plates.

Real geologic faults[edit]

Normal fault

In a normal fault, the hanging wall (the lower wall; right) moves downward relative to the footwall (the upper wall; left). The Earth's crust is extended in this type of fault.

Reverse fault

A reverse fault is basically the opposite of a normal fault. The hanging wall (left) moves upward relative to the footwall (right), and the Earth's crust is compressed.

Transverse fault

A transverse fault, also known as a transform fault, is where the two plates move parallel to each other, but in opposite directions.

Thrust fault

A thrust fault is when older rocks are pushed (or thrust) on top of younger rocks. The angles are typically lower (more horizontal) than in reverse faults.

Fictional faults[edit]

Taffy fault

This appears to involve one tectonic plate, that is being stretched out like a piece of taffy. Ductile crustal thinning of this type actually occurs in rocks under tension at sufficient depths. Such deformation is not a fault, however, as there is no fracture along which movement takes place.

Splinted fault

This appears to be a normal or reverse fault that someone has attempted to fix in position by attaching a large splint, as you might with a broken bone. This is unlikely to prove effective.[citation needed]

Squeezed-bar-of-soap fault

Two plates seem to be moving towards each other, while a third smaller plate is squeezed between them and pushed upwards, much as a slippery bar of soap might pop up when squeezed between two hands.

Apple power cable fault

The plate appears to have been twisted and bent so many times that parts of it are fraying and the end is splitting apart, similar to a damaged Apple MagSafe connector.

Brio fault

BRIO is a company from Sweden that makes wooden toys, including train sets. The Brio fault seems to be two tectonic plates which join together like the Brio train track pieces do. (However, this join is obvously incorrect because of the height difference.)

(Title text) Torn-bag-of-potato-chips-where-the-tear-is-rapidly-growing fault

The title text refers to when a bag of chips gets a tear in it. When this happens, any further stress on the bag, such as reaching in to get more chips, can easily increase the size of the tear, sometimes very quickly. It would be frightening to live near a fault that behaved like this[citation needed] because it could cause major seismic events very quickly. If you were close enough to the fault, you might be afraid that the crack would grow underneath you, causing you to fall into the bag of chips — or, rather, the Earth.


[The comic shows nine different schematic views to present geographic faults and some more.]
[Two planes with a slip fault drifting away to the left and right.]
Normal fault
[Two planes with a slip fault drifting against each other from left and right.]
Reverse fault
[Two planes moving sideways away from each other.]
Transverse fault
[The left plate is moving over the right plate, while the right plate is sliding under the left one]
Thrust fault
[Two planes drifting away and the connection between them gets smaller, like a piece of taffy candy.]
Taffy fault
[On top of both planes a small piece with splints holds them together.]
Splinted fault
[The two planes pressing together with a piece in the middle moving upwards.]
Squeezed-bar-of-soap fault
[The right plane is connected to the left and swinging up and down.]
Apple power cable fault
[One side with a thin connector and the other with an evenly spaced hole connecting the planes together. The pieces fit together like a puzzle.]
Brio fault


Faults have been mentioned several times in xkcd. Thrust faults were previously mentioned in 1082: Geology, and in the title text of 1388: Subduction License, Beret Guy tells Cueball he can't be a 'normal' roomate because in his motion he is creating a reverse fault.

A similar joke to the Apple power cable fault is used in 1406: Universal Converter Box.

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Faults are not necessarily caused on plate boundaries - they can happen anywhere. 04:41, 10 August 2017 (UTC)

Totally missed an opportunity for a Lego Fault. 13:43, 9 August 2017 (UTC)

Both LEGO and BRIO in the same comic would have been too many toys. 14:38, 9 August 2017 (UTC)
I agree, but I think he should have gone with Lego instead, more universally recognized. I know "Brio" as a Spanish Cola. :) NiceGuy1 (talk) 02:41, 11 August 2017 (UTC)
BRIO connections can slide, like most faults, whereas LEGO connections interlock, and don't tend to slip. 12:51, 11 August 2017 (UTC)
Also one must consider that BRIO is from the very south of Sweden, which I think most people can relate to, while LEGO is from Denmark which I think would alienate most of the readers.

The alt text reminds me of how Earthquakes are depicted in movies, where a massive rift opens up in the Earth. 13:48, 9 August 2017 (UTC)

I was totally expecting the Amigara Fault in there 14:10, 9 August 2017 (UTC)

Probably only for Germans, but the comedian Otto Waalkes invented that soap bar long ago in the seventies: Keili. --Dgbrt (talk) 16:01, 9 August 2017 (UTC)

No seg fault to the left or right of the image? Unfortunate. 16:56, 9 August 2017 (UTC)

A segmentation fault in geology sounds absolutely terrifying! And you thought it was a bad deal when it happened to a computer program!

Your fault: 💔 SilverMagpie (talk) 19:24, 9 August 2017 (UTC)

Well, the "taffy fault" is named as a joke, it is quite similar to "rift faults". These are several normal faults going on at the same time at both sides of a valley. The "soap fault" is not impossible.

Another terrifying thing about living near a bag-of-chips fault is that usually the things near the tears in chip bags get eaten. 04:48, 10 August 2017 (UTC)

The "soap fault" is nothing but two reverse faults with a narrow wedge between them. A geologist would refer to the two faults separately, but to the general public, "soap faulting" would be a clear, and accurate, term.

The "splinted fault" is probably related to the plates used to fix broken bones.

The "Apple Power Cable Fault" I took as less a reference to MagSafe connectors and more a reference to iDevice power cords (both the old 30-pin and the current Lightning), whose shielding is so soft and fragile, this kind of tearing always happens, even with the most gentle handling. Actually, it hasn't seemed like the MagSafe connectors have had this fragility problem, at least not to me. NiceGuy1 (talk) 02:38, 11 August 2017 (UTC)

  • If the "soap fault" actually occurred, we would probably have a name for it, like we do for the similar formations called horsts and grabens. But it just doesn't seem to be how the crust behaves. D5xtgr (talk) 03:15, 11 August 2017 (UTC)
I think if the Soap fault were real, it would be incredibly dangerous. Messing with its structural integrity or mass in a significant way would doubtless trigger a quake. Parts calving off the great wall of faultlandia during a quake would potentially exacerbate the issue, and it would likely be prone to weathering in ways that encourage instability. Worse still, it could be thousands of miles long, vertical, near-vertical, or overhanging cliffs miles tall, and rivers or huge waterfalls would flow off both sides. Earthquakes could cause considerable changes in elevation either up or down, or in areas where it generates an exposed cliff face, cause chunks of rock the size of small mountains to calve off. In other words, it would be an utterly-impassable cliff or mountain-like structure that was prone to huge earthquakes and shedding debris onto anything nearby. Any infrastructure you tried to use to go through or over it would need to deal with these quakes and would cost an absolute fortune to build and even more to maintain against continuous Earthquakes. 08:06, 11 August 2017 (UTC)
we should ask michael bay about this... https://xkcd.com/748/

The description for torn-bag-of-potato-chips reminds me a lot of the geological situation in florida, where much of the state is sitting on top of a giant aquifer instead of bedrock. As the aquifer is depleted for use as agricultural and civic fresh water, the structural integrity of Florida itself is increasingly compromised and lately has threatened to swallow up buildings into sinkholes. 18:12, 11 August 2017 (UTC)

A growing-tear-fault should be easy to prevent on bags that allow mid tear steering: if you cross-tear the seam (instead of pulling/tearing across the seam) then just after you start tearing the bag open you can take one of the two tears that forms and (after letting it form a good opening) steer it to the other. (the forces that concentrate on the tear's endpoint should now work on the open air instead of the bag and do diddlysquat instead of worsening the tear) 08:58, 19 October 2021 (UTC)