Puerto Rico is small and very densely populated. It sits 1000 miles out in the Atlantic in what seems to be a hurricane highway. Its needs are much different than the mainland. No one is going to get there for sometime when the big storms hit. On the mainland it is much faster to assemble and move infrastructure into place following an event. With Puerto Rico, the low band station you mentioned could probably cover its land mass. On the mainland it is a different story. FM is line of sight. TV, I've never even considered for weather type emergencies when the lights go out. AM would have a bigger reach, but dial around and you'll see that not much effort is going on to make most local AM stations relevant. I still question the ability of most broadcasters to respond to disasters with limited staff to go live during events. Portable phone and satellite receivers can be brought in to effected areas to restore that kind of communication with a fair amount of speed after a mainland weather event. You even stated that most AM stations today are useless because of their technical facilities. Very true. In the Hudson Valley we have had a number of stations with tower issues. WRKL, New City, NY lost a tower a while back because of lack of maintenance. WGHQ Kingston, went omni directional at lower power in order not to have to maintain a three tower directional array. I question if a lot of undermaintained AM stations would lose towers in a big weather event. Except for some skywave, rural areas will probably not have much information until the national guard brings in the portable cell service. People know a storm is coming for some days in advance. They tend to have stocks of things they need and they also have a choice to leave the area Earthquakes and wild fires come with little warning so that is a different set of issues, as is the circumstances of the densely packed isolated island of Puerto Rico. In any event there will be loss. It is unavoidable, but I don't think you can honestly depend upon local radio stations and I don't think the skywave signals are going to serve rural effected areas to the degree you seem to believe they will.