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Course: American Museum of Natural History > Unit 4
Lesson 2: Volcanoes- Volcanoes 101
- Volcanoes: Magma Rising
- Monitoring Mount Etna: Magma on the Move
- Follow the Magma
- Yellowstone—Monitoring the Fire Below
- Yellowstone National Park is a Volcano
- Scientists at Work: Hawaii
- Quiz: Volcanoes
- Exploration Questions: Volcanoes
- Answers to Exploration Questions: Volcanoes
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Yellowstone—Monitoring the Fire Below
Three of the most catastrophic volcanic eruptions in geologic history occurred at a place now visited by nearly four million people a year: Yellowstone National Park. The magma chamber responsible still lies beneath, and continues to steam, heat, and shift the park landscape. We talk with the geologists regularly monitoring these disquieting signals to understand where this active region lies in its volcanic lifespan. Created by American Museum of Natural History.
Want to join the conversation?
- geysers are made of hot water right?(2 votes)
- ya that's where the hot water comes from(6 votes)
- how does the the mud turn into hot water(3 votes)
- Mud is a mix of dirt and water, so when enough heat is applied, the water evaporates as steam.(3 votes)
- is lava like fire if it is why is there underwater volcanos?(2 votes)
- Yes, there tons of underwater volcanoes. Even though they are are underwater, they can still cause major damage.(3 votes)
- I never knew that the hydrogen bubbles thing is something to be aware of and it happens more frequently with volcanoes. I never knew about the hydrogen thing at all.(2 votes)
- How did the water boil with fire underneath ?(2 votes)
Video transcript
[elk noise] [harmonica] What is special about Yellowstone is up to every individual to define. It can be everything from the beautiful clear
skies of night to, uh, watching wolves, to, uh, just enjoying being out
in nature. [harmonica music] From a geologist standpoint... the volcano is what makes Yellowstone
Yellowstone. [harmonica music] [running water] There are different definitions of what an active
volcano is. And to the public, an active volcano is one that's erupting. Now. Uh, to a geologist, there are a couple of different
definitions, and one of them is simply that it's been active in the last 10,000
years. That there's been an eruption. Um, at Yellowstone, there hasn't been an
eruption of magma in the last 10,000 years. But we see so many other indications that show
that the system is alive, it's breathing. And there's fire below that could again come to the surface in the future. To understand the story of what's going on at Yellowstone, you have to look down in the mantle of the
Earth. [background music] And there is a hot spot that’s down there where
rocks are being melted. This region is melting, you can think of sort of
as a blowtorch and it's melting the Earth's crust. And when that crust melts, it creates magma
chambers high up in the Earth. Such as the magma chamber that's sitting
beneath us at Yellowstone. And when that erupts, we get large volcanic activity. [background music] Some of the eruptions that have occurred at
Yellowstone are among the largest volcanic eruptions that have ever been recorded on Earth. Recorded in the geologic record, that is. And, uh, for example, the one that occurred
640,000 years ago, is on the order of 1000 times more material than
was erupted at Mt St Helen's eruption in 1980. Scientists have become quite successful at predicting on a short-term level whether a volcano's going to erupt or not. The most likely things that we'll see is some significant ground deformation, where the ground is moving significantly upward. We'd also combine that with seismic activity. Earthquakes. You might also expect some sort of a thermal anomaly where we see increased gas flux or increased heat flux in an area. This is a pool called Black Pit. And it's in the Norris Geyser Basin. And we are sampling the gases and steam that are coming out of this feature. We know that magmas are down there, they're putting off a lot of gas. So our goal as geochemists is to collect the gases and try to sort out what's happening one, two, three miles below us. And so we can look at the ratios of different gas species. Say, carbon monoxide to carbon dioxide, hydrogen to hydrogen sulfide, and we can try to unravel the temperatures and the pressures beneath us. I don't think that anything is due for us in the near future. I don't think that's very likely. I do think that Yellowstone is an active system, and it can have eruptions in the future. And so our job is to make sure that we are prepared, and that we know what's going on. Volcanos aren't the only thing that are happening in Yellowstone. In fact, large hydrothermal explosions are much more frequent and pose much more of a immediate hazard, a local hazard, than the volcanic activity does. The original magma chamber is still at depth beneath Yellowstone. And it's a huge mass that's still hot, and trying to cool and crystallize. So that big hot body is still there. But it's contributing the heat that we see in Yellowstone and warming the water that causes the hydrothermal features that we see. Such, as the fumaroles, the hot springs, the geysers. [harmonica] [banjo background] A hydrothermal explosion is basically a hot water event. And at some point in time, something triggers the water in the hydrothermal system to now flash into steam. [banjo background] And so you have all of a sudden this explosion of material mostly hot mud, water, and rock fragments. Over the last 14,000 years, we estimate there are somewhere between 20 to 25 large, 100 meter in diameter, hydrothermal explosions in Yellowstone National Park. We're on the shores of Northern Yellowstone Lake at Mary Bay. The Mary Bay explosion event was the largest, or is the largest documented, hydrothermal explosion in the world. It's crater diameter is about 2.6 kilometers. And it extends all the way over to those green grassy cliffs, or bluffs, across the lake. This lake now occupies the explosion crater, and it's just one very good reminder that hydrothermal explosions are a very real hazard from when that happens much more frequently than volcanic activity does in Yellowstone. [harmonica] If we did have the kind of eruption that has occurred, at Yellowstone in the past, it would be a major national event. There would be ash distributed over many of the nearby states. It would probably get as far as the Mississippi river in some cases. It's an extremely unlikely thing to happen. Again, it's only happened several times here over 2 million years. But it's something that people have to be aware of. [harmonica] I'm not so concerned. I think these are natural processes and this is how the Earth is formed. [harmonica] These are the largest volcanos on Earth. [harmonica] And they really shaped our landscape in a dramatic way. [harmonica]