At risk of sticking my nose in from UK, What is the scenario regarding the
apparently/allegedly overdue supervolcano brewing up under Yellowstone, and
its
aftermath?

Can U be more specific? What did you read.
Only thing I know is that 20 years ago, the USGS said that there absolutely
will be a huge earthquake from the San Andreas fault, but they do not know
when. It will be so big many people will die.
Is this what you are talking about?