Monday, October 23, 2017

The incredible 'Atlas of the Underworld' reveals 94 ancient tectonic plates lurking deep within Earth By Cheyenne Macdonald For Dailymail.com

The incredible 'Atlas of the Underworld' reveals 94 ancient tectonic plates lurking deep within Earth

  • The 'Atlas' compiles 94 ancient tectonic plates, known as slabs, in the mantle under Earth's surface
  • Some of these have sunk more than a thousand miles beneath Earth's surface over time
  • This process has given rise to major mountain ranges and volcanoes from the Himalayas to the ‘Ring of Fire’
By Cheyenne Macdonald For Dailymail.com
Published: 17:48 EDT, 19 October 2017 | Updated: 17:48 EDT, 19 October 2017
Scientists have created an ‘Atlas of the Underworld,’ compiling the remnants of 94 ancient tectonic plates that now lie deep beneath Earth’s surface.
The atlas spans roughly 300 million years of Earth’s history, revealing how different geological processes changed the face of our planet.
Some of these slabs have sunk more than a thousand miles into the mantle, according to the researchers, giving rise to some of Earth’s most extraordinary features, from the Himalayas to the Pacific ‘Ring of Fire.’
Scientists have created an ¿Atlas of the Underworld,¿ compiling 94 slabs of ancient tectonic plates that now lie deep beneath Earth¿s surface. The atlas spans roughly 300 million years of Earth¿s history. The image above show the Cocos 
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Scientists have created an ‘Atlas of the Underworld,’ compiling 94 slabs of ancient tectonic plates that now lie deep beneath Earth’s surface. The atlas spans roughly 300 million years of Earth’s history. The image above show the Cocos 
The incredible catalogue of the ‘underworld’ is 17 years in the making, according to Ars Technica.
Dutch scientists Douwe van der Meer, Douwe van Hinsbergen, and Wim Spakman of Utrecht University published their work in the journal Tectonophysics this month, interpreting 94 distinct slabs.
Some of these slabs have sunk more than a thousand miles into the mantle, according to the researchers, giving rise to some of Earth¿s most extraordinary features, from the Himalayas to the Pacific ¿Ring of Fire.¿ The graphic above shows some of theses slabs, ranked by depth
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Some of these slabs have sunk more than a thousand miles into the mantle, according to the researchers, giving rise to some of Earth’s most extraordinary features, from the Himalayas to the Pacific ‘Ring of Fire.’ The graphic above shows some of theses slabs, ranked by depth
And, they’ve already identified two more.
The ‘slabs’ represent ancient tectonic plates that have sunk below the surface.
With recent seismic tomography techniques, researchers are now able to create 3D images of the hidden processes at work deep underground, revealing slabs as far as 2,900 kilometers (1801 miles) deep.
‘At subduction zone plate boundaries, one plate disappears below another and sinks into the mantle,’ the authors explain on the website dedicated to their work.
‘These sinking plates, called “slabs,” are colder than their surroundings, and remain colder for a very long period of time – about 250 million years.
‘As a result, the speed at which seismic waves travel through these bodies of sinking lithosphere is a little higher than from the surrounding hot mantle.’
Once these plates have descended to the mantle, they can remain there millions of years.
But, they do not stop moving. 

WHAT ARE TECTONIC PLATES? 

Tectonic plates are composed of Earth's crust and the uppermost portion of the mantle. 
Below is the asthenosphere: the warm, viscous conveyor belt of rock on which tectonic plates ride.
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The Earth has fifteen tectonic plates (pictured) that together have molded the shape of the landscape we see around us today
Earthquakes typically occur at the boundaries of tectonic plates, where one plate dips below another, thrusts another upward, or where plate edges scrape alongside each other. 
Earthquakes rarely occur in the middle of plates, but they can happen when ancient faults or rifts far below the surface reactivate. 
These areas are relatively weak compared to the surrounding plate, and can easily slip and cause an earthquake.

While these plates may slow down, the researchers note that they eventually make their way from the upper mantle to the core-mantle boundary.
In creating the Atlas, the researchers have interpreted when and where the many slabs in Earth’s upper and lower mantle were subducting.
The work not only sheds light on the activity beneath the surface, but could also improve our understanding of ancient climates and the activity of mantle hot spots.
The incredible catalogue of the ¿underworld¿ is 17 years in the making. Dutch scientists Douwe van der Meer, Douwe van Hinsbergen, and Wim Spakman of Utrecht University published their work in the journal Tectonophysics this month
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The incredible catalogue of the ‘underworld’ is 17 years in the making. Dutch scientists Douwe van der Meer, Douwe van Hinsbergen, and Wim Spakman of Utrecht University published their work in the journal Tectonophysics this month
As Earth’s geological activity is under constant study, the researchers expect there will be many improvements to their interpretations.
Already, they’ve identified more slabs than detailed in the paper.
‘We have found two more in the eastern Mediterranean region,’ van Hinsbergen told Ars Technica.
‘In Southeastern Australasia, in the deeper lower mantle, we do see more slabs; however, there isn’t sufficient geological literature available to date these.’ 
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