Imagine there is a catastrophic earthquake — 7.8 magnitude — in Southern California. Roadways have been taken out, so have cellphone towers as well as the critical infrastructure for water and power.

Over the course of the next four days, 400,000 Californians head to Arizona for refuge. What do we do?

That was the scenario that played out at Papago Park as part of the National Mass Care Exercise last week. It involved more than 1,000 players from 745 federal, state, local and tribal agencies. Here in Phoenix, about 300 people participated.

The goal was to make sure that Arizona’s emergency response networks are prepared for the absolute worst-case scenario and iron out any unforeseen challenges before that actually happens.

Charlie Misra, with the Arizona Department of Emergency and Military Affairs, walked The Show through the exercise.