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EAS 217 F20

EAS 217 Course Website for Fall 2020

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Global Impacts Video

  • When it comes to measuring the movements of plate tectonics, how accurate are these measurements by using topography(on-site)? Did these measurements match satellite measurements?

    -Josue Criollo

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  • The videos for me were very interesting. It was a mix of reviewing the basic concepts and ideas we learned in class and previous lectures, and finding out new things that I didn’t know. For example, I always thought that any plate boundary would be hot because of the activity itself characteristic of every boundary. But in the “Plate Tectonics Basics” video is mentioned how the crust could be hot or cold in a convergent plate boundary.  It didn’t make sense to me that the crust could be cold considering there is melting happening in this type of boundary. But I understood later that it does make sense since this melting is occurring several meters down while is subducting under the other plate, and is cold on top since the crust would be several kilometers away from the hot divergent boundary/oceanic ridge it formed in the first place.

    Now, is the second video “Plate Tectonics Global Impacts” that mentioned hot spots and it remembered me about a daily doubt I have with the subject. The most common example to explain hot spots is Hawaii and the chain of volcanoes present. I always wondered, when the volcanoes move away from the hot spot, do they stop having magma right away? Can they still cause strong eruptions? Or eruptions at all? What’s the process exactly of becoming an inactive volcano?

    These video are very informative and interesting.

    To clarify, why Atlantic ocean has only spreading?Why not subduction happening?

    -Abigail Doris

    I was also wondering if there is some sort of model to predict when the next supercontinent will form and what it may look like. I do not think there is a specific equation for it, but after a quick google search I found that geologists have hypothesized what the next supercontinent may look. To answer your first question, there were other supercontinents before Pangea and there will be more to come.

    These two videos taught me a lot of interesting information. What I found really interesting was that 45 million years ago India collided with Asia and this collision is still going on today. This is causing the Himalayan Mountains to continue growing. I did not know that, and it made me think about how fast the Himalayan Mountains may be growing. Another question I had while watching the video on Plate Tectominc Global Impacts was what happens or what is present where the three ridge ocean centers meet in the Indian Ocean?

    these videos shared some thoughtful knowledge about the place we are living in. However, if we are assuming that there were more than just one super-continent, why is Pangea the mainstream.

    I found it very interesting when it talked about the formation of the Himalayas and the volcanic mountain ranges in California and other along the coastal boundaries of other plates, yet one of the largest mountains was left out. Denali, or Mount McKinley, has a bigger body than Everest, more elevation gain from base to peak. I was wondering what would’ve caused such a large mountain to form there? I suppose it would’ve been something similar to the Himalayas, where two continental plates collided, if so which plates? I thought it surely would’ve been mentioned in the video if it was notable enough but alas, here we are.

    In the videos we learnt that there are four different layers of Oceanic Crust: Pillow Basalts, Sheeted Basalt Dikes, Gabbro, and Sediments. Are there layers that can be identified in continental crust? Which of them are the same? The only one I can think of is the Sediments layer.

    What I found most interesting was water’s effect on the asthenosphere at a subduction zone. Because it reduces the melting point of the asthenosphere, it causes it to melt and the molten magma thereby becomes less dense and rises to the surface along with the water. The sheer amount of water at a subduction zone is what causes such explosive volcanoes to exist and my question is how much water is required to create such an explosion?

    I found it super interesting to learn about pangea and how our continent’s placement came to be. My favorite part of the video when they showed the triple junction where three different seafloor spreading centers come together and showed actual pictures where you can see the new rift zone appearing. It was mentioned that about 45 million years ago India collided into asia in a continent continent collision and is continuing to do so, and that made me wonder if it would ever stop? Also in millions of years from now, will the placement of the continents be completely different from how we see them now?

    I personally found the subject of supercontinents quite interesting because it seems that (like everything else on earth) it is a cycle. The last supercontinent to form was Pangaea and there were six supercontinents that  have formed and dismantled before Pangaea was formed. Considering there is knowledge of the speed at which the continents move and which directions, is there a computer simulation that depicts a prediction of when  the next supercontinent forms and how it could possibly look like?

    Something that I found interesting from the second video was that there was that there is a diverging spreading center on both the Northwest coast and in the Gulf of California in Mexico. From the simulation they played on the video, it looked as if land was moving in from the South-Southeast to make the west coast of America longer.  I know that plates move very slowly, at speeds of millimetres per seconds, so it would take thousands of years before it would be a noticeable difference, but does this imply that in some thousands of years later the west coast would have moved a sizable distance even further to the west?

    It may be kind of like a boiling pot of soup. Sometimes the froth on top is all pushed over to one side (a lot of upwelling in one area)… but in the case of the Earth the froth is an insulator, so it can get hot under the supercontinent area, and this can eventually cause the supercontinent to break up again and spread out.

    The EQ happen cluster along plate boundaries. The depth and intensity aren’t really related.

    At any trench, it will be one plate going under the other… even if it’s at a triple junction.

    20 meters/year??! whoa. Some things that would happen would be that the sea level would rise tremendously because the ocean crust would be warmer and less dense everywhere. So the continents would be flooded. Also, as you said, there would be a lot more volcanic gasses… my guess, probably still possible for a human to survive, but it would a very different place.

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