I was photographing landscapes in a field under high tension power lines (see photo) when I discovered my metal tripod was delicately vibrating. I could only feel the vibrations if I rested my fingers lightly on the metal and they were clearly related to the high tension wires (not the gentle breeze). When I moved the tripod away from the lines the vibrations stopped, but returned when I took it back beneath the wires again. What was going on? More importantly, if the lines did this to a metal tripod, what might they have been doing to my body?

Alistair Scott, Gland, Switzerland