Infrared cameras and cave detection

[Bumbalawski]

I had posted this reply on another thread, but thought it may help some with a question concerning this cave detecting technique.

I have a hand held FLIR E4 camera. It cost right at $1000. It can be hacked to E6 capabilities prior to a certain camera mfg. date. Mine is hacked to the E6, which is an immense improvement over the out of the box E4. I use it for cave detection since I am a caver. We use it in digging out sinkholes and warm spots. Some sinks are trash filled with various metals. Unless in direct sunlight and exposed to the sun, the metals do not give off a different temperature reading than the surrounding soil. Even in direct sunlight, buried metals do not display a different heat signature than the surrounding ground. At least what I have noticed to date. I will perform some field test in the near future to see if there is anything to this theory. It does work well with airflow detection, which is a primary tool for finding caves. But it is done usually around 60° and above and 32° and below, since cave temperatures vary from low 40's to upper 50's, depending on the cave environment.

These pictures are an example of a cave entrance issuing cold air down the from the entrance. The entrance was not visible from below and the original entrance was no larger than a groundhog hole. I have been very successful finding new caves using this technique.

 

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[stefen]

What I'm seeing is soil and litter in a shadowed area (void of being a reflective or heat sink)...which doesn't appear to be a cave much less a groundhog burrow.

A convincing demonstration would be full excavation of the entrance of an actual cave having a scale larger than a bear den or badger hole.

 

[Bumbalawski]

The cave is over 1200 feet long and no end in sight. We just have not been able to get back to it since we have many projects. Believe me, this method works. We have found many new caves with the FLIR. The entrance is well above the airflow and not pictured. This attachment is one of the rooms in the cave.

 

[CaptEsteban]

Very interesting !

 

[celtic fox]

hi bumbalawski does this cave look like it goes on in your opinion it looks like it was an underground river as its like a circular tube land ownersays it opens into large cavern https://youtu.be/TE5UfitBA4Y

 

[Blake.]

Do you have a picture of the entrance? I’m in search of a cave and have been using a FLIR one pro and found very similar pictures as yours. I am trying to figure out where to begin. Just start digging there around it?

 

[A2coins]

Holy moly that really cool

 

[Bumbalawski]

Sorry, I have not been back to this thread for a long time. This cave is a serious blower. We opened a couple of caves up above it about a mile and 800 feet higher in elevation. The development of the formation is limited in thickness, so we have determined these are upper entrances. In the winter, they suck air in and the lower cave blows air. In the summer, it is the opposite. Thus, over a mile of passage is possible with 800 feet of vertical relief. You may doubt this, but across the road on the south side of the water cut, are caves in the same formation. The one cave over there is surveyed at 7000 feet (roughly 35% surveyed) with 470 vertical feet of relief. As for the FLIR, I use the "cold spot" setting for outside above 55° to detect lower entrances. When the temps are below 55°, I use the 'warm spot" setting to detect upper entrances. If you find a location of several hot or cold spots that are concentrated over a small area, take the hottest or coldest reading dig there. Always 'follow the air". If it is sucking air, use a small smoke test determine the path of air flow. The pictures are of the entrance after we opened it.

 

[hvacker]

Your method with the usual karst sightings seems like a good tool.
I used to use an anemometer to help judge the amount of blow an
entrance had but had to be aware of the time of day as blow can
become suck when the cave breathes. I was trying to equate the
velocity with cave size. The opening was sometimes hard to estimate.
Digital revolution has made anemometers affordable.

 

[Bumbalawski]

One of our guys Corey, does also use an anemometer. We found that a constricted passage with large passage further in, will produce an accelerated airflow at the constriction. We call it the "venture effect". Another observation is with water. I have found airflow associated with decent water flow. The water appears to drag the air along. We also have a few caves in our neck of the woods that pulse. These caves have a large volume of passage with entrances around 3 foot and less. When an area is hit with a gust of wind in the general area of the cave, the air pressure will increase in the cave will increase depending upon the wind speed of the gust. The interior of the cave will charge, then pause for a given time, and then discharge with a sizable force. Then we have one cave that defies logic. The entrance is the current high point with 500 feet of vertical relief. There are no other known entrances. In the winter, it will blow air and the summer reversal will not occur until 80 degrees. There is another one like it 6 miles north in the same ridge that does the same thing.

 

[hvacker]

That might be a very large cave. If a cave blows at all it has to have two sources or there would be nothing to blow.
I wonder if the cave next door has a connection.
I remember when Mammoth Cave connection was made. It was so tight only this small woman, 110 lbs., could squeeze through. The squeeze was aptly named. My memory might not be right but something like "The Birth Canal."
The group entered an area in Mammoth called the dining room. Big event but no one was there. It was a Sunday and the park was closed. Bummer.

 

[hvacker]

Bumbalawski quote:
"One of our guys Corey, does also use an anemometer. We found that a constricted passage with large passage further in, will produce an accelerated airflow at the constriction. We call it the "venture effect". "


Yes a constriction changes static pressure to velocity pressure. Like rocks in a fast river. This is a dynamic of any fluid.
There are probably too many variables to judge a cave size by it blow. At least not w/o funding.

Because of your experience with IR someone might ask can it be used to find other things underground. I have seen a forum here that has some saying they can see gold with IR.

 

[Bumbalawski]

I have seen the 'gold claims' with the IR cameras. I looked a little at the theory, but am still out to lunch about it. I would bury some gold and test the theory, but financial embarrassment prevents that test. We were looking for a cave and buried articles a few years ago. A friend with an $8K metal detector assisted in the search. We got a faint hit with the detector in a fissure. We later excavated the area of the fissure with a 315 CAT excavator and found a void about 12-15 feet from the place where the detector picked up the signal. No metal was found. He said the MD was not suppose to pick up voids, but obviously it did. I thought only two box MD's picked up voids.

 

[hvacker]

Knowing the amount of air escaping might be useful over a period of time. Maybe an average over
days and seasons might yield something useful.
If interested in the math to arrive at a number to gauge the blow off of it goes like this.
Take the rough area of the opening in inches. Rough average width times the rough height average.
Divide by 144 to get the square feet. Then take the average velocity in feet per minute X the area
to get the CFM (cubic feet/minute. CFM in feet/min=area in square feet x velocity in feet per min.
You or your buddy might already know this. Just in case. It might be fun.

 

[hvacker]

In the paper yesterday there was a report from a development at Sandia National Lab of an IR antenna
on a nano scale so small it can't be seen on top of the detector array.
The detector can boost the signal to IR cameras by three times and improve image quality by reducing dark
current that is a component of image noise by 10 - 100 times.
They say it's ready to begin applications in security and astrophysics. Now we need the camera. There are
people on this forum that use IR to find gold they say.