"...if this type of disaster were to hit a large population center in the US, similar situations would ensue."

Look at the section of SoCal from the Los Angeles metro area east to the Riverside/San Bernardino area, as a possible site of a major disaster area. Sixteen million people. Add a major earthquake. This is mostly a desert area. There are a few dams, but most of the water is piped in, and both those sources could be damaged or destroyed in a major quake.

Is there anyone naive enough who thinks even water (never mind medical help or food or toilet paper) could be distributed to all of those people within a week? Yes, many.

Having been born and raised there, I can visualize a disaster of incredible size. And what if it happened in summer?

Sue, shuddering