So, in addition to prayer, how to prepare?
You and your family should discuss this and have a PLAN. You can also get many ideas online. Where would you all be to be in a relatively safe place? How will you get there? Would you remain where you are? How will you communicate with one another? Prepare as you would for any lengthy disaster, asking God to guide and protect you and/or, if in a neighborhood, get to know everyone and work together to prepare (protection, sharing of resources/talents/skills, etc.).
Even though the thought of all this still seems just *OUT THERE* ...it’s looking MUCH more probable than ever before. You may find some really practical ideas here too: https://thepeppyprepper.wordpress.com