Soil scientists and some conservationists will tell you that 95% of what's a centimeter underground is unknown as well.

I read somewhere E. O. Wilson stating that were he to start over again he would go into research of life in the soil. He also said there is so little we understand about the things just beneath our feet.

We don't even know how to document it all when we extract DNA from soil. You might be able to put things into general families of species but too much is uncharacterized. Some research is opting to just consider things in terms of ecological niches occupied instead of absolute species found.

Even on, and in our feet.

There's an aquatic cave in Death Valley called Devil's Hole; divers have gone to ~600 ft, but the cave is likely over twice as deep.

A magnitude 7.6 earthquake 1,500 miles away caused 4 ft high waves at Devil's Hole: https://www.cbsnews.com/news/mexico-earthquake-triggers-4-fo...

It may be that the aquifer in Devil's Hole is somehow connected to a network of underwater aquifers thousands of miles away in Mexico… but we just don't know, and have no way of knowing right now.

Can’t we just use some form of ultrasonic wave from one end and detect at other end ?

I’d imagine the amount of energy you’d have to push into the water would be insane to hear it 1500 miles away, wouldn’t it?

Whale noises travel thousands of kilometers underwater. https://en.wikipedia.org/wiki/Whale_vocalization

There's an inverse relationship between wavelength and range, and the higher the frequency the better the resolution.

https://acousticstoday.org/wavelength

What other end?

Pour in some traceable mix of chemicals, and see if it turns up somewhere.

There're these fish called the Devil's Hole Pupfish. Can't do that.

There is a near infinite number of non toxic chemicals to choose from.

Ah, but can you show that they're not toxic to Devil's Hole Pupfish? And the population is tiny and fragile--you're not allowed any test subjects.

There might well be 5 separate regulations forbidding it. That's a different question.

The safest class of substances I can think of are unusual isotopes.

They're chemically identical to the regular elements, which is what matters for life forms, but can be detected by scientific instruments.

You'd deafen the poor troglobites.

As your link says, it's a seiche. https://en.wikipedia.org/wiki/Seiche .

> Earthquake-generated seiches can be observed thousands of miles away from the epicentre of a quake.

https://weather.com/news/video/how-mexicos-earthquake-caused... says the waves started about 20 minutes after the earthquake, which was 1,500 miles away. That's about 2 km/sec, which makes it (I think) due to the S-wave.

It's certainly not underground water being compressed for hundreds of miles before arriving at Devils Hole, if only because underground water flow doesn't work that way.

Seiches happen even in swimming pools, as at https://www.youtube.com/watch?v=-2JwUSD3x2s where the pool starts sloshing around from an earthquake about 200 miles away. They don't need to be connected to a larger water system.

I see from https://en.wikipedia.org/wiki/Devils_Hole :

> The pool has frequently experienced activity due to far away earthquakes in Japan, Indonesia, Mexico, and Chile, which have been likened to extremely small scale tsunamis

and https://home.nps.gov/deva/learn/news/alaska-quake-shakes-wat... notes the Alaska earthquake was 2,000 miles away in the other direction.

Who named it?