The military starting in about 1985 implementing a low frequency (approximately 174kHz) ground wave emergency network (GWEN). This is currently managed by TG-2 Minimum Essential Emergency Communications (MEECN) with about 58 towers completed to date (240 planned). The initial stated purpose was to be used in case of high-altitude detonation of a nuclear device. About $500 million has been currently spent. "Airforce I" is reported to have an antenna for use of GWEN. A 180 page study was completed in 1993 at the request of US Air Force, and Congress, that sells for $33.00. This is an assessment of the potential Health Effects, or lack of effects, associated with the deployment of the GWEN system. The public began to strongly resist and construction stopped for a while in the early 1990s. The following is some Internet references.
Summary: With the military considering GWEN as minimum essential communications what does that tell you. What do you bet GWEN is not used during and after the pole shift by some one. I suspect an emergency ham network could be developed along these lines using a more optimum (for us) frequency. Not quite so low.
Offered by Mike.