Saturday, October 19, 2019

What Happens under the Yellowstone Volcano



Yellowstone National Park in the US is a major attraction for tourists with its geysers and hot springs. Especially in times of low news, however, the media focus is often on the super volcano Yellowstone, which erupted for the last time around 630,000 years ago.

 At the latest then the question of the underlying geological structures is asked. A recent study by Bernhard Steinberger from the German GeoForschungsZentrum and colleagues in the USA helps to better understand the processes in the Earth's interior. The work will soon be published in the journal "Geochemistry, Geophysics, Geosystems" of the American Geophysical Union. It is based on the modeling of the mantle.

The model results show a high similarity with interpretations from seismic waves. The circles mark remnants of the ancient Yellowstone crater (Calderen), suggesting that the continental crust has moved westward. The "Mantel Plume" under the Hot Spot is tilted and has its origin under the Baja California 
Credit; CC BY 3.0: Bernhard Steinberger).


Thus, there is a so-called mantle Plume under the Yellowstone volcano: a structure similar to a chimney, which stretches thousands of miles deep to the border of the earth's core and mantle. The origin of the plume lies under the "Baja California", more than a thousand kilometers southwest of the national park. Evaluations of earthquake waves had already suggested such a thing, but the idea of ​​such a "mantle plume" did not match the movement of the lithospheric plates.

The model results show high similarity with interpretations from seismic waves. The mantle plume below the hot spot is tilted with its origin below Baja California. (CCBY 3.0: Steinberger/GFZ)
Credit: Steinberger et al.

It is clear that Yellowstone is a so-called intraplate volcano. Most volcanoes in the world are at the boundaries of continental plates, either where material is swelling up from the Earth's interior, as in the Mid-Atlantic Ridge, or where one continental plate dips and melts beneath the other, as it does along the entire South American west coast is. In contrast to plate-edge volcanism, intraplate volcanism goes back to "hotspots" beneath the earth's crust. This can be imagined as a welding torch, which melts the rock plate from below - where a hole is blown, a volcano grows. That's how Hawaii, for example, came into being.

However, the seismic data for Yellowstone did not provide a clear picture for a long time. This has been changed by new data and refined measurement methods, which allowed the deeper part of the plume to be imaged in a tomographic image. However, there were gaps in the upper mantle. The data was not so clear here. The study from the GFZ now fills these gaps with a modeling result that depicts the cloak Plume consistently with the observation data. 

Accordingly, there are movements of the viscoplastic rock in the lower mantle, which move relative to the surface to the south-southwest. Like the plume of a steamer, the plume drifts from the Baja California to the north-northeast to the Yellowstone volcano. Bernhard Steinberger: "Our study contributes to a better understanding of intraplate volcanism and supports the hypothesis of a deep mantle plume. But for the risk assessment of the Yellowstone volcano this has no effect. "

Original study: B. Steinberger PL Nelson, SP Grand, W. Wang, 2019: "Yellowstone plume conduit tilt caused by large-scale mantle flow". Geochemistry, Geophysics, Geosystems; DOI: 10.1029 / 2019GC008490 (accepted and reviewed version, in print) http://dx.doi.org/10.1029/2019GC008490







Contacts and sources:
Josef ZensJosef ZensHelmholtz Center Potsdam German Research Center for Geosciences GFZ

Dr. Bernhard Steinberger
Section Geodynamic Modeling
Helmholtz Center Potsdam German Research Center for Geosciences GFZ









2 comments:

  1. I am blogging this. https://ysamok.wordpress.com/2019/10/20/new-study/

    I don't know what the study means, but my sleepy
    little Yellowstone blog has huge traffic. And the whole west coast is beating like a drum ...

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