<p>There are three main types of waves produced during an earthquake: P, S, and L waves, which stands for Primary, Secondary, and Love. (There was a mnemonic I read many years ago that went P=pressure, S=Shear, and L=Long.) The P and S waves are body waves. That is, they propagate inside the earth.  The P wave is basically a sound wave; as the mnemonic goes, a pressure wave.  The S wave is a shear wave and is perpendicular to the direction of fault slip.  The L wave, which has the highest amplitude is a surface wave and, as such, propagates along the surface, not inside.<br><br>If you were inside a cave when a nearby earthquake occurred, you would not feel the L waves, since they propagate along the surface. Whether or not you would feel the P and S waves would depend mainly on two things: the magnitude of the original earthquake and the type of fault that produced it. If the fault were a thrust fault, the S wave would be up and down, which a standing person probably wouldn't feel unless the earthquake was quite large (>5.5?).  However, if the earthquake were along a strike-slip fault, the S waves would be side to side, which a standing person would likely feel.<br>(I realize this answer duplicates some of that given by @stali, but I was already typing this when I saw that answer come across, and I thought I had some additional thoughts in this answer.  Sorry for the duplication.)</p>

CC BY-SA 3.0
2015-07-14T18:52:30.103Z
2015-07-14T18:52:30.103Z
BillDOe
<p>Googling leads to a very old document: <a href="http://www.geo.arizona.edu/gsat/1887eq/historical/Stanton_1918_BSSA.pdf" rel="noreferrer">EFFECTS OF AN EARTHQUAKE IN A MINE AT TOMBSTONE, ARIZONA</a> stating that in many cases, mine workers did not notice earthquakes which were felt above ground. </p>

<p>A newer book, <a href="http://link.springer.com/chapter/10.1007%2F3-540-28500-8_18" rel="noreferrer">Earthquake effects on tunnels</a>, check the "Look Inside" option for the introduction) confirms this. According to this source, a possible reason is that overground structures are less constrained in their movement while inside solid rock, the displacement cause by the earthquake is much smaller. </p>

<p>Apparently your guide was right.</p>

CC BY-SA 3.0
2015-07-14T17:02:28.797Z
I still think you would feel the quake if you were close to where it occurred - how could you not? I agree that somebody in a cave in Volcano, California, may not feel a quake in San Francisco, whereas it may be felt on the surface, but I believe those in the cavern would feel a quake whose epicenter was in Volcano itself. IOW, if the statement was chaned to, "an earthquake felt on the surface may not be felt below the surface," I'll buy that.
B. Clay Shannon-B. Crow Raven
CC BY-SA 3.0
2015-07-14T16:58:13.403Z
2016-09-27T12:13:22.020Z
2016-09-27T12:13:22.020Z
Christoph
<p>Ground motion results due to passage of elastic waves. Now there are different kinds of waves, e.g., P waves, S waves, surface waves, etc. Most of the shaking (and therefore damage) is caused by surface waves. So if you are in a deep cave or mine then the amount of shaking you might experience can be much lower than on the surface. This of course assumes that the mine or cave is not right on the fault, but some distance (10s of km) away.</p>

<p>Having said that, there are some situations (based on the type of earthquake and local geology) in which waves can interfere constructively to cause significant shaking even at large depths, but this only happens in certain areas and not everywhere.</p>

<p>In many ways elastic wave propagation is similar to acoustic or water waves. Imagine a small explosive source in a lake/pond, let's say 50&nbsp;m underwater. After the explosion there will be more 'shaking' on the surface, but not much underwater unless you're extremely close to the explosive source.</p>

CC BY-SA 3.0
2016-02-08T01:13:37.750Z
@JoeKington: Wouldn't your animation only be relevant for the surface waves? I would think that something like this example of [underwater explosions exerting pressure on balloons](https://youtu.be/M5gHFJyMQ6o) would be more relevant for pressure waves travelling through the crust.
naught101
CC BY-SA 3.0
2016-02-08T01:16:52.077Z
@naught101 - The P and S waves aren't damaging. You'd barely be able to feel them. Only the surface waves produce enough ground acceleration to have a significant effect.
Joe Kington
CC BY-SA 4.0
2020-01-06T08:30:30.040Z
@JoeKington link is expired
Sri Ram
CC BY-SA 3.0
2015-07-14T18:43:33.447Z
As a visual example: http://faculty.gvsu.edu/videticp/wave_animation1.GIF  The water analogy is more-or-less exact (for Raleigh waves, anyway) in this case.
Joe Kington
CC BY-SA 3.0
2015-07-14T19:38:14.970Z
Local geology, as @stali mentions, have an often underestimated impact of the intensity. I'm no  speleologist, but most caves I know about are in limestone or hard igneous rocks. Shaking hazard is much more severe in soft sediments: http://earthquake.usgs.gov/regional/nca/soiltype/
user2821
CC BY-SA 3.0
2015-07-21T22:08:55.933Z
I would expect, from @Tbbe 's comment, that caves in regions or materials that feel earthquakes aren't likely to last long enough to be observed -- instead being collapsed by earthquakes. Worst case would to be in a newish cave when a long-quiet fault becomes active, then.
cphlewis
CC BY-SA 3.0
2015-07-22T06:23:55.013Z
@cphlewis Caves can be common in some tectonic active regions and there are examples of rather old systems, but yes, e.g. a cavity situated under unconsolidated lake bed sediments would probably collapse rather quick (even without an earthquake). Interested in how caves are formed should look up karst forming and developing processes.
user2821
CC BY-SA 3.0
2015-07-22T06:26:29.053Z
Still, as answers are pointing out, surface waves have the highest amplitude on the surface, that's where the strongest impact is. Think about the analogy of shaking a completely full and a half full bottle. The micro-environment in the full bottle would be much more healthy than being in a bottle where the water is not hold in place by the walls, even if acceleration is the same.
user2821
CC BY-SA 3.0
2015-07-14T18:22:06.880Z
2015-07-21T01:12:18.983Z
2015-07-21T01:12:18.983Z
stali
<p>I took a tour of a cave in northern California last weekend. The tour guide asked us, "<em>If an earthquake occurred, what would we feel in here?</em>"</p>

<p>My answer was, "fear," but she said we would feel nothing - that earthquakes are not felt underground.</p>

<p>Although I did not contest her assertion, I have my doubts about it - after all, don't earthquakes normally have their epicenter underground (well, <em>all the time</em>, I reckon, as they can't emanate from the air)? And if an earthquake happened to erupt from within a cave[rn], wouldn't it most definitely be felt there?</p>

<p>I would think one might even end up with a stalagtite stuck in his noggin.</p>

<h2>UPDATE</h2>

<p>And, if I'm right (that there could be a whole lotta shakin' goin' on while on a journey to the centre of the earth), has anybody lived to tell the tale and really done it (told the tale)? A first-hand account could be riveting.</p>

CC BY-SA 3.0
2017-08-24T00:57:49.077Z
When the 2011 earthquake hit in the northeast US, I was in NYC in the subway when the earthquake hit. I don't know if it was the trains shock absorbers or the tunnel, but I felt nothing. I didn't realize there was an earthquake until I left the subway and saw a sea of people on the streets that had evacuated the sky scrapers.
Christian A Soto
CC BY-SA 3.0
2017-10-29T15:17:43.710Z
@Christian A Soto: Do you mean the *[2011 Virginia earthquake](https://en.wikipedia.org/wiki/2011_Virginia_earthquake)* (2011-08-23)?
Peter Mortensen
CC BY-SA 3.0
2015-07-14T15:45:04.610Z
The epicentre is on the surface by definition, but the [hypocentre](https://en.wikipedia.org/wiki/Hypocenter) is certainly below the surface.
gerrit
CC BY-SA 3.0
2015-07-14T23:36:25.977Z
I think this question needs a quantitative answer... it would be nice to see a model, or some data from seismometers at *vs* beneath the surface. The present answers are rather arm-wavy, since the short, direct answer to the question (not to mention the intuitive one) seems to be **No** — indeed, [this report](http://www.osti.gov/scitech/servlets/purl/6441638/) indicates that there can be substantial damage underground if peak ground acceleration at the surface is high.
Matt Hall
CC BY-SA 3.0
2015-07-15T03:30:19.910Z
Earthquakes are definitely felt in basements. I can't imagine any mechanism which would keep them from being felt in natural caves.
keshlam
CC BY-SA 3.0
2015-07-15T13:12:07.093Z
_Tunnelling and Tunnel Mechanics_ by Kolymbas have a short chapter on earthquakes. The author states that; 'Experience shows that underground structures, especially deep ones, are far less vulnerable to earthquakes than superficial ones' and list reasons and a few references. 
http://link.springer.com/chapter/10.1007%2F3-540-28500-8_18
user2821
<geology><geophysics><earthquakes><seismology>
Is it true that earthquakes are not felt in a cave?
B. Clay Shannon-B. Crow Raven
# Is it true that earthquakes are not felt in a cave?

(Asked by: username_0 on 2015-07-14)

I took a tour of a cave in northern California last weekend. The tour guide asked us, "*If an earthquake occurred, what would we feel in here?*"

My answer was, "fear," but she said we would feel nothing - that earthquakes are not felt underground.

Although I did not contest her assertion, I have my doubts about it - after all, don't earthquakes normally have their epicenter underground (well, *all the time*, I reckon, as they can't emanate from the air)? And if an earthquake happened to erupt from within a cave[rn], wouldn't it most definitely be felt there?

I would think one might even end up with a stalagtite stuck in his noggin.

## UPDATE

And, if I'm right (that there could be a whole lotta shakin' goin' on while on a journey to the centre of the earth), has anybody lived to tell the tale and really done it (told the tale)? A first-hand account could be riveting.

**Tags:** geology, geophysics, earthquakes, seismology

> **Comments:**
> **username_3**: The epicentre is on the surface by definition, but the [hypocentre](https://en.wikipedia.org/wiki/Hypocenter) is certainly below the surface.  
> **username_4**: I think this question needs a quantitative answer... it would be nice to see a model, or some data from seismometers at *vs* beneath the surface. The present answers are rather arm-wavy, since the short, direct answer to the question (not to mention the intuitive one) seems to be **No** — indeed, [this report](http://www.osti.gov/scitech/servlets/purl/6441638/) indicates that there can be substantial damage underground if peak ground acceleration at the surface is high.  
> **username_5**: Earthquakes are definitely felt in basements. I can't imagine any mechanism which would keep them from being felt in natural caves.  
> **username_6**: _Tunnelling and Tunnel Mechanics_ by Kolymbas have a short chapter on earthquakes. The author states that; 'Experience shows that underground structures, especially deep ones, are far less vulnerable to earthquakes than superficial ones' and list reasons and a few references.  http://link.springer.com/chapter/10.1007%2F3-540-28500-8_18  
> **username_1**: When the 2011 earthquake hit in the northeast US, I was in NYC in the subway when the earthquake hit. I don't know if it was the trains shock absorbers or the tunnel, but I felt nothing. I didn't realize there was an earthquake until I left the subway and saw a sea of people on the streets that had evacuated the sky scrapers.  
> **username_2**: @username_1: Do you mean the *[2011 Virginia earthquake](https://en.wikipedia.org/wiki/2011_Virginia_earthquake)* (2011-08-23)?  

---

## 3 answers

### Answer by username_9 on 2015-07-14. Score: 26 | Accepted answer

Ground motion results due to passage of elastic waves. Now there are different kinds of waves, e.g., P waves, S waves, surface waves, etc. Most of the shaking (and therefore damage) is caused by surface waves. So if you are in a deep cave or mine then the amount of shaking you might experience can be much lower than on the surface. This of course assumes that the mine or cave is not right on the fault, but some distance (10s of km) away.

Having said that, there are some situations (based on the type of earthquake and local geology) in which waves can interfere constructively to cause significant shaking even at large depths, but this only happens in certain areas and not everywhere.

In many ways elastic wave propagation is similar to acoustic or water waves. Imagine a small explosive source in a lake/pond, let's say 50 m underwater. After the explosion there will be more 'shaking' on the surface, but not much underwater unless you're extremely close to the explosive source.

> **Comments:**
> **username_11**: As a visual example: http://faculty.gvsu.edu/videticp/wave_animation1.GIF  The water analogy is more-or-less exact (for Raleigh waves, anyway) in this case.  
> **username_6**: Local geology, as @username_9 mentions, have an often underestimated impact of the intensity. I'm no  speleologist, but most caves I know about are in limestone or hard igneous rocks. Shaking hazard is much more severe in soft sediments: http://earthquake.usgs.gov/regional/nca/soiltype/  
> **username_13**: I would expect, from @Tbbe 's comment, that caves in regions or materials that feel earthquakes aren't likely to last long enough to be observed -- instead being collapsed by earthquakes. Worst case would to be in a newish cave when a long-quiet fault becomes active, then.  
> **username_6**: @username_13 Caves can be common in some tectonic active regions and there are examples of rather old systems, but yes, e.g. a cavity situated under unconsolidated lake bed sediments would probably collapse rather quick (even without an earthquake). Interested in how caves are formed should look up karst forming and developing processes.  
> **username_6**: Still, as answers are pointing out, surface waves have the highest amplitude on the surface, that's where the strongest impact is. Think about the analogy of shaking a completely full and a half full bottle. The micro-environment in the full bottle would be much more healthy than being in a bottle where the water is not hold in place by the walls, even if acceleration is the same.  
> **username_10**: @username_11: Wouldn't your animation only be relevant for the surface waves? I would think that something like this example of [underwater explosions exerting pressure on balloons](https://youtu.be/M5gHFJyMQ6o) would be more relevant for pressure waves travelling through the crust.  
> **username_11**: @username_10 - The P and S waves aren't damaging. You'd barely be able to feel them. Only the surface waves produce enough ground acceleration to have a significant effect.  
> **username_12**: @username_11 link is expired  

---

### Answer by username_7 on 2015-07-14. Score: 17

There are three main types of waves produced during an earthquake: P, S, and L waves, which stands for Primary, Secondary, and Love. (There was a mnemonic I read many years ago that went P=pressure, S=Shear, and L=Long.) The P and S waves are body waves. That is, they propagate inside the earth. The P wave is basically a sound wave; as the mnemonic goes, a pressure wave. The S wave is a shear wave and is perpendicular to the direction of fault slip. The L wave, which has the highest amplitude is a surface wave and, as such, propagates along the surface, not inside.  
  
If you were inside a cave when a nearby earthquake occurred, you would not feel the L waves, since they propagate along the surface. Whether or not you would feel the P and S waves would depend mainly on two things: the magnitude of the original earthquake and the type of fault that produced it. If the fault were a thrust fault, the S wave would be up and down, which a standing person probably wouldn't feel unless the earthquake was quite large (>5.5?). However, if the earthquake were along a strike-slip fault, the S waves would be side to side, which a standing person would likely feel.  
(I realize this answer duplicates some of that given by @username_9, but I was already typing this when I saw that answer come across, and I thought I had some additional thoughts in this answer. Sorry for the duplication.)


---

### Answer by username_8 on 2015-07-14. Score: 15

Googling leads to a very old document: [EFFECTS OF AN EARTHQUAKE IN A MINE AT TOMBSTONE, ARIZONA](http://www.geo.arizona.edu/gsat/1887eq/historical/Stanton_1918_BSSA.pdf) stating that in many cases, mine workers did not notice earthquakes which were felt above ground.

A newer book, [Earthquake effects on tunnels](http://link.springer.com/chapter/10.1007%2F3-540-28500-8_18), check the "Look Inside" option for the introduction) confirms this. According to this source, a possible reason is that overground structures are less constrained in their movement while inside solid rock, the displacement cause by the earthquake is much smaller.

Apparently your guide was right.

> **Comments:**
> **username_0**: I still think you would feel the quake if you were close to where it occurred - how could you not? I agree that somebody in a cave in Volcano, California, may not feel a quake in San Francisco, whereas it may be felt on the surface, but I believe those in the cavern would feel a quake whose epicenter was in Volcano itself. IOW, if the statement was chaned to, "an earthquake felt on the surface may not be felt below the surface," I'll buy that.  

---

