字幕表 動画を再生する 英語字幕をプリント Hey, good news! I live, right down the road from one of the largest volcanoes in the Earth's history. So here in Montana, it's beautiful, we have a tone of breweries, and chai shops and lovely parks to take my dog to, which is why I sort of have a hard time imagining it being completely destroyed and covered in 6ft burning hot ash and pumice. But, you know me, I live for danger. The fact is, just 250 miles from me lies one of the Earth's largest volcanoes, which you probably know as Yellowstone National Park. And it is still active, though it's not one of those cool, mountainous, oozy volcanoes that Hawaii gets. The Yellowstone volcano is one of a half-dozen or so tantruming mountains that earn the title supervolcano, because its eruptions can eject nearly 250 cubic miles of ash, dust and gas. For comparison, that's about a thousand times the volume of Mount St. Helens' eruption in 1980, which was in itself a pretty big deal. But you shouldn't be surprised, the Yellowstone is famous for its hydrothermal features, like geysers and hot pots and fumaroles, which are all products of this volcanic hot spot, where half-melted magma swirls up close to the Earth's crust. But the problem is, when Yellowstone goes all Christian Bale on us: "Oh, good for you, yeah, you see, you're walking around, duh-tara-tahrah, going through your fumaroles, yeah, I'm gonna kick your #[email protected]&%*! Which it has done three times in its history. Those eruptions were so huge that you can actually still see their effects from space. This ring that surrounds Yellowstone National Park is a crater, or caldera that was caused by a series of eruptions that happened 2.1 million years ago and we can still see them. The first of them was the largest, which left a divot in the ground the size of Rhode Island and deposited ash so far away that the rock formed from that ash, called tuff, can still be found from Los Angeles to St. Louis. The second happened about 1.3 million years ago, was the smallest of the three, still managed to leave a 23-mile-wide crater in eastern Idaho. And the most recent, about 640 thousand years ago, was less than half as big as the first, but still equal to about 2500 Mt. St. Helens', covering hundreds of miles of western north america in a foot of ash. Now, to give you a sense of how mind-blowingly huge these events were, here is how the Yellowstone's greatest hits compare to some other gigantic eruptions. I can't believe I live in the same area code as that thing. Now, there were no people around when the Yellowstone last erupted, but history has shown us what some of its colleagues have done, and it's not pretty. The most recent supervolcano eruption happened about 75 thousand years ago when mount Toba blew its lid in what is now Indonesia. Toba spewed probably around 720 cubic miles of stuff into the atmosphere, sent sulfuric acid rain falling as far as Greenland, and six inches of ash fell in India. And scientists think that all of this debris spewed in the upper atmosphere actually caused a miniature ice age which we can see in the geological record. Ice core samples show that the Toba eruption was followed by a global decrease in temperature of five to nine degrees that lasted hundreds of years. Or maybe that was just a coincidence? We can hope?! So, I know you're wondering whether or not you should cancel your plans to come visit Montana, ehh, first of all, no, you can totally crash on my couch. Secondly, the geologists at the Yellowstone volcano observatory, which is a thing that I'm glad we have, say that if they could predict the eruption of this massive supervolcano, which they can't, it wouldn't be overdue for another 100 thousand years or so. So, there is that, at least, and I hope that you come and visit Yellowstone soon, because it's pretty freaking cool place. Ahh, even if it is one day going to kill us all. Thank you as always for watching. If you would like to ask us questions, or suggest topics for us here at scishow, please suggest them on Facebook, or Twitter, or in the Youtube comments below and don't forget to subscribe. Because, we're making you smarter.