Showing posts with label geology. Show all posts
Showing posts with label geology. Show all posts

Monday, January 24, 2011

A Deep Surge of Magma Shakes Yellowstone, Lifts Ground 10 Inches

More: Brian Wang at NextBigFuture has more information and some reassurances
Yellowstone National Park sits atop a subterranean chamber of molten rock and gasses so vast that the region, known for its geysers and grizzlies, is arguably one of the largest active volcanoes in the world.

Granted, it's not your typical volcano, either in scale (it's huge), appearance (it's a vast depression, not a single mountain) or frequency of eruption (at least hundreds of thousands of years apart).

But it is active, and the evidence is everywhere. _Discovery


One of the world's great supervolcanoes sits and waits beneath Yellowstone National Park in Wyoming. It has erupted before and it will erupt again, someday. Recent quaking of the ground in Yellowstone, combined with ground surges as high as 10 inches, have caused some geologists to wonder if the clock may be ticking down to another big blow.
"Clearly some deep source of magma feeds Yellowstone, and since Yellowstone has erupted in the recent geological past, we know that there is magma at shallower depths too," said Dan Dzurisin, a Yellowstone expert with the USGS Cascades Volcano Observatory in Washington State.

"There has to be magma in the crust, or we wouldn't have all the hydrothermal activity that we have," Dzurisin added. "There is so much heat coming out of Yellowstone right now that if it wasn't being reheated by magma, the whole system would have gone stone cold since the time of the last eruption 70,000 years ago."

The large hydrothermal system just below Yellowstone's surface, which produces many of the park's top tourist attractions, may also play a role in ground swelling, Dzurisin said, though no one is sure to what extent.

..."Big quakes [can have] a relationship to uplift and deformations caused by the intrusion of magma," he said. "How those intrusions stress the adjacent faults, or how the faults might transmit stress to the magma system, is a really important new area of study."

Overall, USGS's Dzurisin added, "the story of Yellowstone deformation has gotten more complex as we've had better and better technologies to study it." _NatGeo
It is not easy to predict a volcanic eruption. Supervolcanoes may be even more difficult to predict -- no one knows. It will take time to acquire enough experience with the immense geological processes taking place beneath our feet. The video below provides a sobering look at the aftermath of a Yellowstone super-eruption.

Monday, December 20, 2010

Massive Amounts of Water Entrained Into Earth's Mantle

SD

As oceanic crustal plates grow and butt against continental plates, they subduct under the continental plates. As they dive into the Earth's mantle for "re-cycling", these ocean crusts carry large quantities of water and sediment with them. Geologists are learning more about what happens to the subducted water.
Scientists know: many volcanoes need water for their eruption. In the upper mantle, water lowers the melting temperature of the rocks. As a consequence, it melts faster and can ascend in form of magma to the Earth's surface. In areas where an oceanic plate is pushed underneath a continent by plate tectonics processes, large quantities of water reach the interior of the Earth.

Such a region, called subduction zone, can be found at the west coast of Latin and South America. Through large cracks formed during the subduction process of the oceanic plates water penetrates, is partly captured and transported in the mantle. There, high pressure and temperatures squeeze it out of the subducting plate and the water ascends back to the surface. On the way back it supports the formation of magma. Therefore all subduction zones are characterized by volcanoes at the continental margin.

"So far we knew that the entrainment of water into the Earth's mantle in the area of subductions zones is substantial and that it is released again by volcanic process. Nevertheless, the exact path of the water down to the mantle and back to the surface had so far not been shown in one unifying context," explains Tamara Worzewski, geophysicist in the Collaborative Research Centre (SFB) 574 "Fluids and Volatiles in Subduction Zones -- Climate Feedback and Trigger Mechanisms for Natural Hazards" who has investigated these processes. Together with Dr. Marion Jegen and Prof. Dr. Heidrun Kopp from the Leibniz Institute of Marine Sciences at the Christian-Albrechts-Universität (IFM-GEOMAR) in Kiel and colleagues Dr. Heinrich Brasse from the Freie Universität Berlin and Dr. Waldo Taylor from Costa Rica, she was able to show for the first time the complete water path from the seafloor down to 120 kilometre depth and back to the surface using electromagnetic methods.

The study, now published in Nature Geoscience, is also part of Worzewskis PhD Study. _SD

PBS
Regular readers of Al Fin and Al Fin Energy will be aware of these blogs' interest in hydrocarbons that find themselves inside the Earth's mantle. But the fate of water in the mantle can be closely tied to the fate of much of the organic carbon which finds its way into the mantle by the same subductive process. Volcanic eruptions clear a great deal of both water and carbon from the mantle, along with other gaseous and mineral matter. It is part of the ongoing geologic cycles of the planet.

And yet, massive amounts of crustal organic carbon and mantle hydrocarbons persist long enough to migrate and transform into potentially economic reserves of "fossil fuels." Most of this resource will remain unkown to humans, despite a great deal of it settling within the growing technological and economic reach of humans.
We have barely begun to learn the basics about our planet, our climate, our solar system, our portion of the spiral arm of the Milky Way Galaxy, and so on. How absurd it is that pseudoscientific quasi-religions such as catastrophic anthropogenic global warming orthodoxy, or peak oil DOOM!, should find such large, gullible, and enthusiastic followings.

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