Fascinating. Any references? A cursory web search reveals nothing.

This is basically hilarious. Leaky Feeders are a few watts. and even a high powered multi-kW AM radio with 200m wavelength wouldn't resonate much in a rough walled tunnel multiple sq meters in cross section. It's both too large for there to be significant power density, and much less than a wavelength in diameter except in length where the tunnel passively attenuates the signal.

Fascinatingly false.