We have yet in recorded history seen the worst of the solar storms.
They hit with such voracity of the solar storms; the monster of all storms happened a little bit over 12,500 years ago. It was strong enough to melt a 1000 foot thich sheet of ice that lay over most of the northern continenets.
We know the exact year after studying ice cores; they found one where surface started heating, culminating in a 40 degree surface temperature increase. That would have to be one hell of a blast to melt that much ice that quickly, making it look like a flood. The oceans did rise 60 to current levels.
That is a lot of ice and the critics to this would imply no solar storm could melt 1000 foot sheet of ice. I would answer that is because you have not seen one yet of that intensity.
Do you want more proof?

I give Velikowsky and his proof of the catastrophe proof.
Or even the Portland and the Columbia River Gorge, that was carved out in
this time period. It started near Sandpoint Idaho, where the end of the Ice Age melted so quickly that it released a torrent of water all the way to the coast.  The lake is so deep the US Navy still uses it for acoustic research.

Even the pyramids in Mexico and Bosnia were covered with a top still and had vegetation growing on them.

This appears to have happened more than once. Mankind is specially vulnerable to these monster solar storms.

The Derinkuyu underground city  is an ancient multi-level underground city in the Derinkuyu district in Nevşehir Province, Turkey. Extending to a depth of approximately 60 m, it is large enough to have sheltered approximately 20,000 people together with their livestock and food stores. It is the largest excavated underground city in Turkey and is one of several underground complexes found across Cappadocia.
Why build an underground city? It will do you little good from your enemies. They would just have to light things on fire and throw them down the ventilation shafts. No it was build to protect them from something else. Might I suggest monster solar storms.

And so that brings us to the question s to way the Federal Government is making large underground cities.