Earthquake in Caving Country

[L Roebuck]

Hey did any cavers feel the earthquake (magnitude 3.3) last night?

Earthquake Hazards Program

[Brian Roebuck]

I'm pretty sure I slept right through it. If you go to the website there are reports from hundreds of miles away where people claim to have felt it though. Very interesting! I thought it might be another big room under Spencer forming/collapsing but alas the report puts the earthquake seceral miles deep - well below the limestone.

[Sharon Faulkner]

Guess I slept through it too Lynn, of course the epicenter would have probably needed to be a bit closer for us to sense it here in Alabama.

I didn't feel the Magnitude 6 earthquake in the Gulf of Mexico last fall either and people as far away as Atlanta reported experiencing some trembling.

[Brian Roebuck]

I've experienced trembling while driving through Atlanta. Does that count? ;D

[dhparker]

Earthquakes and caves brings up a question I've wondered about for a long time. (Nothing to do with writing, I was just curious.)

We took a tour through Onondaga cave in MO several years ago. Being not far enough from the New Madrid fault, somebody asked the guide about earthquakes. He said earthquakes didn't bother caves. I figured he had to say that to avoid panicking tourists. I didn't, and still don't, see how it could be true. Surely any force that could heave up mountains and split the earth wouldn't necessarily spare caves. Any comments?

[L Roebuck]

Good questions! I wish I had the answers.

I understand this earthquake was very near Camps Gulf Cave. According to the USGS site the most distant points the quake was felt and reported was in Daleville Virginia and Delaware Ohio.

[Brian Roebuck]

dhparker said:

Earthquakes and caves brings up a question I've wondered about for a long time. (Nothing to do with writing, I was just curious.)

We took a tour through Onondaga cave in MO several years ago. Being not far enough from the New Madrid fault, somebody asked the guide about earthquakes. He said earthquakes didn't bother caves. I figured he had to say that to avoid panicking tourists. I didn't, and still don't, see how it could be true. Surely any force that could heave up mountains and split the earth wouldn't necessarily spare caves. Any comments?

I have heard from many sources that earthquakes are wave phenomina that flow through "solid" ground rather than waves in the ocean which travel in water. Just like waves in the ocean they are rather mild in height and are spread out horizontally until they reach to the surface. If you have ever ducked under a big ocean wave to more easily ride it out that on the surface you know what I mean. Thus earthquakes will likely be much less violent underground than above it where at the surface there is nothing to constrain the vertical movement of soils, rocks, and everything on it. Of course I wouldn't want to experience a New Madrid type quake while in a cave. Even that would be too violent for my tastes! I suspect some rockfall could occur as well as shifts in floors and some breakdown piles during earthquakes. It could be very dangerous if you were in a tight spot or beneath loose rocks or breakdown.

[Sharon Faulkner]

I've read a few trip reports from cavers who have been in a cave during small earthquakes. Each report said that the group heard a rumbling type noise, but did not feel any movement and did not learn it was an earthquake until afterwards.

Yes, Dr. Beaner, driving through Atlanta traffic is justifiable cause for trembling with or without an earthquake. ;D

[dhparker]

Nope. Never have ducked under an ocean wave, Dr. B. I make it a point to stay out of the ocean as much as possible. Ocean is almost as scary to me as Atlanta traffic. ;D

Very interesting information, though. Thanks, everybody. Maybe the cave guide wasn't just trying to preempt panic.