In general it’s going to be a disaster, but people are prepared for it (as much as one can be anyhow)
More precisely, it's 8, the average is 500 years, and the last one was in 1700.
The results I've seen (from a decade and a half ago) pegged the probability of a magnitude > 9 in the next 50 years at 1/10 and a magnitude > 8 at 1/3.
The 500 years average is if you look at the last 7 events. 7 is a horribly low sample size and if you extend the timescale, that average drops by half and indicates we are past the 250 year average.
There is a fair bit of variability in the 500 year average, and 8 is still a seriously large earthquake, so preparations are definitely justified IMO.
- stockpiles of food and medicine
- various shelters
- excess local manufacturing capacity
- transparent, public, reviewable plans for different contingencies
- subsidized making normal consumer devices more robust (e.g. repairable, RF-hard, etc. -- anything which can be done at reasonable cost)
- training and coordinating responders, including something like the National Guard or territorial defense forces, but more general in scope.
- making sure we can produce everything we need to survive locally (food, medicine, and the infrastructure to support those)
... and so on.
It's hard to predict the next disaster, but we should be ready.
A better plan is for two weeks.
Back in the day, with the first surge of the Avian flu, Governor Schwarzenegger ordered an bought a large supply of respirators, "just in case".
That stock pile was released and not maintained by later administrations. Then COVID hit.
The problem with something like a Carrington event is that the potential impact is very widespread. The large bulk of our disaster planning is local. The planning rightly expects the cavalry to come to the rescue directly. Katrina was a poster child of both a good and bad response. The Houston boat lift is another. The rest of the country rallies and pivots to the disaster area sending material and people to aid the stricken.
Having a 2 week store when you can shelter in place is a Good Plan for a very large majority of potential disasters. It doesn't work great for fire or floods (where you lose your home, and thus have no place to shelter). But the plan is to be able to maintain for the 2 weeks while the cavalry arrives.
The problem with something like a Carrington event, is the disaster is no longer localized. But very wide spread, thus that cavalry that was planned for is probably not coming. Not soon. Not in time. And the rules have changed dramatically. It's a nightmare scenario. Despite the wide spread devastation of the Tsunami, it, too, was localized, and aid flowed quickly, even across the sea. With a Carrington event, not so much.
This is where, ideally, communities must rally themselves, on their own initiative, to share resources and manage as best they can. As you can imagine, some communities may be able to do this better than others. But your 2 week supply for your family is now likely better used to support others in your community. For every Ant preparing for winter, there are a lot of Grasshoppers. And they get unruly when they get hungry.
It would be unprecedented, and the only real course is to muddle through best we can. State and Federal disaster planning may or may not help here. Back in the day, the USDA running the Welfare programs stockpiled and delivered food (the infamous "government cheese"). Today they just offer debit cards. I don't know if there are warehouses of cheese and peanut butter standing by anywhere any more.
Still, you can do you part, you can do your best. Engage with your neighbors, stockpile a bit more food (don't need to fill the garage with a year supply of dried beans, but an extra case of tuna won't hurt). Make your preparedness part of a continuing cycle of giving, as your stockpile starts reaching the 6 month due date, donate it to a food pantry, and get some more. But reaching out to your neighbors can help a lot, get them to work on their 2 weeks supply.
Its not all about guns and gear. It's more about civility, and having a little more food or blankets to share with others in times of crisis. No reason to expect to feed the whole neighborhood, but don't expect them to leave you alone with your stocked garage while they go hungry.
1) We want food production overcapacity, so if there is e.g. a 25% hit due to a freak weather event, or a diseases killing 100% of this years' corn crop, we don't have widespread food shortages.
2) That overcapacity should go somewhere. Large warehouses seem like reasonable places for it to go.
A lot of other things -- like medicines -- I can't realistically manage.
And rotating food is, well, a lot of hard work for someone absent-minded. I think one of my key questions is about how bad expired food gets. I've heard of people eating (and even growing) literally ancient grains. "Best before" isn't always "toxic after."
We used to be able to make big plans like this maybe a 75 years ago, during the era of WWII and the early cold war. Let's stick a man on the moon! Make a nuclear bomb! Create a whole new system of government! Etc.