Geology of Crater Lake National Park
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- čas přidán 19. 07. 2020
- Learn about Crater Lake National Park, the subduction of the Juan de Fuca plate, and how water released from the subducted plate causes melting in the mantle that gives rise to the Cascades volcanic arc.
Thanks for the info and entertainment!
Interesting videos and good explanation
Very well done video. Bummer the channel didn't take off.
Jay, this is an excellent explanation and is very accessible! Thank you!
I often think that these days our perception of how volcanos erupt is often distorted by the way they are portrayed in visual entertainments. I'm thinking of films like '2012' and 'Pompeii'. Whilst much larger than Mt Mazama, the Yellowstone super-volcano would have erupted in a very similar fashion, with multiple vents erupting along the ring faults spewing out ash, rather than the massive single central explosive vent depicted in '2012'. As for the eruption of Vesuvius in the 2014 film 'Pompeii', the film maker admitted adding fireballs for dramatic effect, though nothing of the sort occurred during the eruption. If it had, the volcanologists excavating and studying the deposits the eruption left would have found abundant evidence of such things... and they haven't.
Volcanos are dangerous enough without film makers inventing fictitious dangers solely to make the eruption dramatic. in fact, most explosive eruptions tend to be more messy than movie dramatic, with all the ash they pump out. Also, such eruptions tend to be rather quiet between explosions, and but for the turbulence to be seen in the rising ash column, you might be forgiven for thinking it all quite peaceful.
And yes, when calderas are spoken of, most times it's those formed during big explosive eruptions that are cited. Yet the Hawaiian Islands' shield volcanoes have pit calderas, as do the shield volcanoes of Galapagos, and they really do form in a similar way to sinkholes. I don't know if it can still be accessed, but the USGS had time lapse footage of a caldera collapse event at Halema'uma'u, after the 2018 Lower East Rift Zone eruption drained Kilauea's magma chamber. It was something to see crescent shaped sections of rock quietly slip down several hundred metres: there seems to be so little disturbance of the layers of the blocks it looks possible to stand or sit on the top of the sliding slabs and ride down safely, though this may be a deceptive view.
I was confused by your description of the caldera. You said this kind of volcano does not erupt but instead sinks or collapses into itself. Then you tell how the ash cloud was sent into the air. But isn't that an eruption ? Also I was interested in knowing the distribution of the ash that came from Mt. Mazama, how deep it was, how far it went and whether was there any ejection of solid ? material. Thank you for the video, I hope there are more of them for Oregon geology.
This talks about the distribution of the ash. en.wikipedia.org/wiki/Mazama_Ash
I think the point he was trying to make is that the ash cloud is not from the mountain blowing but it collapsing. If you watch videos of building implosions you can see the shock wave and small bit of dust released by the initial explosions (think the actual volcano eruption). However, the bulk of the dusk comes from when the building collapses in on itself and grinds up its internal structure (caldera collapse).
it is an explosion. The collapsing ceiling seals in the fire and it explodes outward. Just Like a bomb.
If you are Canadian I can forgive you for using the metric system in describing height and depth. However, if you are American (yeah, as in USA. Don't get me started on that made up controversy), you are failing to communicate effectively to you average countrymen (yes, women, too. Another made up controversy) by eschewing miles, feet and inches when describing height and depth.
Plenty of Americans use the metric system on a daily basis, especially those who work in the sciences. Instead of criticizing him for using the metric system, this is a great opportunity for you to learn the metric system. You'll learn that it is really quite useful and intuitive. Being an American doesn't give you an excuse for not learning anything but the imperial system.
Signed,
An American who loves the metric system.
And some think that Esperanto should be the universal language.. As long as pilots refer to their altitude in feet there is still hope for us knuckle dragging, ignorant, moon walking chauvinists. We understand the metric system much the way some of us understand a language other than English. But it is an annoyance to translate words from one language when we dream in another. Same for metric. In an Imperial using culture it slows down the speed in which concepts of space, distance and weights can be comprehended because it must be translated to Imperial in our minds. If the targeted audience is 'Merican the metric system should get parenthetical reference if not eschewed altogether.
I'm sorry, I didn't realise I had to be US-american to be interested in the subject and watch the video. Every science communicator with an aim outside the US should stick to metric, it's the language the world understands.
Apology accepted.