This is such an insane map because a meter of ash is not that much when compared to other volcanoes, let alone a supervolcano. At the center would be dozens of meters of ash. Vesuvius in 70ad poured 60 feet of ash and debris onto Herculaneum and 40 onto Pompeii. Granted that was a pretty big eruption. But still, compared to fucking Yellowstone??

That graphic might be underestimating the damage. The last documentary I saw said a major global extinction was caused by the last one and areas similar to the ones here were scortched, not ash covered. But again, it was a while ago, and memory tends to make things bigger.