sinkholes

melindamusil said:

After a sinkhole forms, at what point can the police/fire tell that it has stabilized?

I remember after that sinkhole in Florida, the emergency responders said that they could not continue recovery efforts because the sinkhole was too unstable and was continuing to grow.

On the other hand, I know there are sinkholes which have stabilized and which are used to explore caves or archaeology.

Do they use ground-penetrating radar to examine the sinkhole? Seems like the radar pulses might cause further instability. What about infrared cameras? Hmm...

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When they stop needing new firefighters cause the old ones fell in?

*rimshot*

Got no idea, sorry.

Cornflake isn't far off. Basically, when it stops collapsing for a while. In Florida, sinkhole capital of the universe, it could keep growing for a long time. Or it could end up a foot across and eight inches deep.

The Atlantic just did a decent article on sinkholes, you might dig that up.

My question would be what you want from a sinkhole as far as your story needs.

Jeff

melindamusil said:

After a sinkhole forms, at what point can the police/fire tell that it has stabilized?

I remember after that sinkhole in Florida, the emergency responders said that they could not continue recovery efforts because the sinkhole was too unstable and was continuing to grow.

On the other hand, I know there are sinkholes which have stabilized and which are used to explore caves or archaeology.

Do they use ground-penetrating radar to examine the sinkhole? Seems like the radar pulses might cause further instability. What about infrared cameras? Hmm...

Click to expand...

There is a tendency for sinkholes to expand, and that tendency doen't end. It is also a matter of what caused the sinkhole. If there is a river in a cave that dcaused the sinkhole then it will keep expanding, and that can happen with limestone caves. If the cavity is of limited size, then eventually it will fll up.

melindamusil said:

think of the scene near the end of the first "National Treasure" movie.

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I'd rather not think of any part of that movie.

Weasel's right. You wait for it to stop slabbing. And then you make a S*W*A*G - scientific wild ass guess.

Firefighters are not engineers, but you develop a seat of the pants approach to collapsing structures. We're constantly dealing with them. You watch to see minor movements, knowing that big movements happen next. You poke and prod, seeing what happens. Something that is stable can take a fair amount of poking and prodding without moving.

Then you balance risk versus benefit. Recovering a body is important, but not worth a lot of risk. Finding a buried kid is worth a lot of risk. Then you start getting equipment and stabilizing what you can.

Firefighters have a wide range of backgrounds, and it's a rare department that doesn't have someone experienced in heavy construction. And if we can't find an expert easily, you call fire alarm and have them find one. I know in the Florida case about the body they brought in some mining experts and some people from the University of Florida who specialize in sinkholes.

Best of luck,

Jim Clark-Dawe

melindamusil said:

Basically, I've got a couple of people stuck in an underground cavern and need to either find or create a new entrance. For lack of a better comparison, think of the scene near the end of the first "National Treasure" movie.

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This kind of changes things since, if they cause a sinkhole on the surface, it means their own ceiling caves in on them. The sand goes somewhere when it sinks through a hole in the rock layers.

Traditional way to find an exit is smoke revealing airflow. A lot depends on the cave, where it is, what it was (mine, natural cavern, etc.) and how deep/far they have traveled. Might start researching spelunking instead of sinkholes.

Jeff

^^ Agree. We have tons of old sinkholes around here, and some new open up even now. Ours are almost always caused by underground streams and rivers that have dried up - ditto the many caves in the area. But if a sinkhole opens up, that earth has to go somewhere - in this case, it would either go on top of your characters or actually block their exit.

melindamusil said:

Thanks guys. My characters just wrote themselves into a corner and I'm trying to figure out how to get OUT of that corner. MMC and FMC are trapped in a cave (underground), but no one else knows about the cave except the bad guy. So I'm trying to find a way for their amigos up on the surface to find them, and/or for them to find another way out.

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If there's a stream through the cave, then let them gamble that the stream comes to the surface; they can just follow itor float on a treetrunk tht slides down the sinkhole.

It may not be at all what you're looking for, but there's a section in "The Moon of Gomrath" by Alan Garner which *still* gives me the willies, where the main characters are stuck underground and end up snaking through a tunnel they're not entirely sure will get them out, which is going up and down with parts of it underwater. It's an older YA book, so it might not be at your local library, but it's a quick read and worth it just to see how the ambiance can be done.

wendymarlowe said:

It may not be at all what you're looking for, but there's a section in "The Moon of Gomrath" by Alan Garner which *still* gives me the willies, where the main characters are stuck underground and end up snaking through a tunnel they're not entirely sure will get them out, which is going up and down with parts of it underwater. It's an older YA book, so it might not be at your local library, but it's a quick read and worth it just to see how the ambiance can be done.

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Do you mean The Weirdstone of Brisingamen, Wendy? Pretty sure that scene is in there, not the sequel.

Cath said:

Do you mean The Weirdstone of Brisingamen, Wendy? Pretty sure that scene is in there, not the sequel.

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Entirely possible - I haven't read those books since I was ten, mostly because that scene creeped me out so much Glad to know I wasn't mis-remembering too badly, though!

It's in Weirdstone of Brisingamen, yup. I didn't know there was a sequel. To Google, post-haste!

A 200' diameter by 90' deep sinkhole has developed over the past few days in Western Kansas - it's still growing.

http://www.cbsnews.com/video/watch/?id=50152246n