The researchers had a helicopter fly a giant transmitter
loop over the landscape, inducing an electrical current in the ground, and measured the resistance to the current as far as 350 meters below the surface (see video below).
Looping and spiralling through the rugged
landscape of the Engadine Valley, our ascent takes us through the Albula Tunnel and
over the Bernina Pass to an altitude of more the 7,000 feet.