I am trying to remember then name of a sci-fi book from the 70/80's - It starts out that scientists were in Cryo in a mountain side in the Northwest - I think. Their chamber had positive air pressure in case there was a leak, they would be safe. The main door to their chamber was bent during an earthquake while they were under and a couple of the cryo chambers were broken and those scientists were dead. They finally get out of the mountain and EVERYTHING has changed in the US. I wish I could remember the title or the author. Any help would GREATLY appreciated.