Can electromagnetic waves be used to search for deep underground water?

Chris Smith put this question to Jess Wade from Imperial College London...

Jess - I think that they do detect deep underground water using this. I think first, you can do it with electricity in a similar way to what we were talking about before about water being non-conductive. You can basically put electricity into rocks and set up two little electrodes and find out water base on how non-conductive your rocks are, so you can make estimates about how conductive different rocks are because of the ions that are inside them.

Chris - But does that tell you that there's a big pool of water at position (X) underground?

Jess - So you can because you can make an educated guess about how conductive a surface should be based on the rocks that there are inside it. And then you can tell how non-conductive it is because of this big body of something that’s basically an insulator. But you can also do much more clever ways, kind of a bit similar to MRI so you can excite the kind of hydrogen nuclei inside water and look at the signals that they give off. And you can use that to estimate again, how much water is under there. And then you can even do more clever things. When you’ve got this water, you can find out how old it is by doing things like carbon dating so you can figure out how old this pool of water is and the kind of flow and stuff like by looking at that.

Chris - And a V-shaped birch log, is that good?

Jess - Yeah, you can do that if you’ve got a nice tree, I think if you're going into that way. But I'm pretty sure you can detect waves underground. You can detect electromagnetic waves underground and that’s actually probably how an awful lot of earthquake detection and stuff like that happens.