Talbot Andrew wrote:

[snip]
 Speculatively of course, this
would be at a frequency in the 60 - 170Hz region - which makes even
amateur 9kHz experiments seem tame.   It is stated that in the US there
are lines looking like old fashioned telegraph wires many hundreds
(1000s ?) of km long carrying signals that make fences spark.
[snip]

For a comprehensive page on the ELF russian submarine communications
system ZEVS at 82 Hz  (!) look here :
http://web.tiscalinet.it/vlfradio/zevs/zevs.htm

73   Alberto   I2PHD