Tectonic plates 'weaker than previously thought,' say scientists

September 13, 2017
Credit: CC0 Public Domain

Experiments carried out at Oxford University have revealed that tectonic plates are weaker than previously thought. The finding explains an ambiguity in lab work that led scientists to believe these rocks were much stronger than they appeared to be in the natural world. This new knowledge will help us understand how tectonic plates can break to form new boundaries.

Study co-author Lars Hansen, Associate Professor of Rock and Mineral Physics in Oxford University's Department of Earth Sciences, said: "The strength of tectonic plates has been a major target of research for the past four decades. For plate tectonics to work, plates must be able to break to form new plate boundaries. Significant effort has gone into measuring the strength of the key olivine-rich rocks that make up plates using .

"Unfortunately, those estimates of rock strength have been significantly greater than the apparent strength of plates as observed on Earth. Thus, there is a fundamental lack of understanding of how plates can actually break to form new boundaries. Furthermore, the estimates of rock strength from laboratory experiments exhibit considerable variability, reducing confidence in using experiments to estimate rock properties."

The new research, published in the journal Science Advances, uses a technique known as 'nanoindentation' to resolve this discrepancy and explain how the rocks that make up tectonic plates can be weak enough to break and form new plate boundaries.

Dr Hansen said: "We have demonstrated that this variability among previous estimates of strength is a result of a special length-scale within the rocks - that is, the strength depends on the volume of material being tested. To determine this we used nanoindentation experiments in which a microscopic diamond stylus is pressed into the surface of an olivine crystal. These experiments reveal that the strength of the crystal depends on the size of the indentation.

"This concept translates to large rock samples, for which the measured strength increases as the size of the constituent crystals decreases. Because most previous experiments have used synthetic rocks with crystal sizes much smaller than typically found in nature, they have drastically overestimated the strength of tectonic plates. Our results therefore both explain the wide range of previous estimates of strength and provide confirmation that the strength of the rocks that make up is low enough to form new plate boundaries."

The study was an international collaboration involving scientists from Stanford University, the University of Pennsylvania, Oxford University and the University of Delaware.

Dr Hansen added: "This result has implications beyond forming tectonic plate boundaries. Better predictions of the strength of rocks under these conditions will help inform us on many dynamic processes in plates. For instance, we now know that the evolution of stresses on earthquake-generating faults likely depends on the size of the individual crystals that make up the rocks involved. In addition, flexing of plates under the weight of volcanoes or large ice sheets, a process intimately linked to sea level on Earth, will also ultimately depend on crystal size."

Explore further: Study of olivine provides new data set for understanding plate tectonics

More information: "Size effects resolve discrepancies in 40 years of work on low-temperature plasticity in olivine" Science Advances (2017). advances.sciencemag.org/content/3/9/e1701338

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Jeffhans1
not rated yet Sep 13, 2017
Large impact bodies could also crack the plates. If it were a high enough energy event, it could even propagate cracks on the antipodal side of the earth as the energy waves resonate.
Chris_Reeve
1 / 5 (3) Sep 14, 2017
Re: "there is a fundamental lack of understanding of how plates can actually break to form new boundaries"

Much like global extinctions which span continents and numerous species, it's only a problem for theorists who assume that the Earth has a past completely unmarked by violent catastrophes.
barakn
4 / 5 (4) Sep 14, 2017
There are no such theorists, so your point is moot.
Maggnus
3 / 5 (2) Sep 14, 2017
Re: "there is a fundamental lack of understanding of how plates can actually break to form new boundaries"

Much like global extinctions which span continents and numerous species, it's only a problem for theorists who assume that the Earth has a past completely unmarked by violent catastrophes.


Another silly comment from the wonderAcolyte! Of course, he is trying to promote the crap from Velikovsky, Worlds in Collision is a fantasy imagined by a charlatan. He was trying to start a new church, he just wasn't as crafty about it as L.Ron.
Chris_Reeve
1 / 5 (2) Sep 14, 2017
What is Uniformitarianism and how did it get here?
Alex Marton

"... the truth of the Biblical story was directly connected to a highly political issue: the legitimacy of the Monarchy ...

In 1807, a small group of amateurs had formed the London Geological Society. In the words of one of its founders, they were starting 'a little talking geological dinner club.' Of the original group of thirteen, four were doctors, two booksellers, one an ex-minister, two amateur chemists who were also independently wealthy, and so on. Only one member had training in geology, but did not pursue it as a livelihood. In fact, an amazing aspect of the London Geological Society is that none of its founders were geologists experienced in or prepared to do field work, but gentlemen inclined to meet for dinner and talk ..."

(cont'd)
Chris_Reeve
1 / 5 (2) Sep 14, 2017
(cont'd)

"Even so, in its second year, the London Geological Society was joined by two dozen Fellows of the Royal Society. Its growth accelerated so much that within ten years, its membership was in excess of 400; in 1825, the year of its incorporation, it was up to more than 630. Though England was going through a busy period of canal building and mine exploration (so that there was plenty of digging going on), the number of active geologists who were members of the London Geological Society was very close to zero. The amateurs who were members were interested in geology not so much because of its practical applications or even for the theoretical speculations of a new science, but because of the religious and political consequences it might have.

In the 18th century, the winds of democracy from America and the attacks of thinkers like Locke and Rousseau, among others, questioned the Monarchy as the natural form of government ..."

(cont'd)
Chris_Reeve
1 / 5 (2) Sep 14, 2017
(cont'd)

"The social context in which these political-religious-scientific battles came to a head in England was the popular restlessness of the early nineteenth century. After defeating Napoleon, England fell into a severe depression. The army was demobilized, throwing almost half a million men into unemployment; the overseas market for British exports dried up; the government's need for war supplies evaporated. A set of laws (the Corn Laws) passed to protect farmers against cheap imported grain resulted in prices so high that workers were unable to buy it. The effects rippled through Britain's farms and industry alike, creating starving workers and bankrupt businesses.

Incidents of popular unrest led the (monarchist) government to enact laws curtailing certain rights. Free speech was one of them. There were those who smelled revolution in the air, but the liberal middle class could still remember the ravages of the French Revolution ..."

(cont'd)
Chris_Reeve
1 / 5 (2) Sep 14, 2017
(cont'd)

"That's not what they wanted. What they wanted was reform in Parliament, but traditional theological doctrine stood in the way. Paley's Natural Theology claimed that sovereignty descended from God to the King; if he was satisfied with it, there was no need to reform it.

Paley's doctrine was required study in the universities, and was the received wisdom in society. There was only one way to reform Parliament, and that was to destroy Paley's Natural Theology - and the only way to do that was to discredit the catastrophist notions of its religious defenders who sought to reconcile the geological evidence with the story of Genesis.

Scientists in Britain and on the Continent had been making discoveries in the geological record that strained the literal interpretation of the biblical story, while others tried to save it by reinterpreting the words (six days were really six eras, and so on) ..."

(cont'd)
Chris_Reeve
1 / 5 (2) Sep 14, 2017
(cont'd)

"Many scientists who were also religious tried to find solutions acceptable to the churches, to the people who were increasingly confused, and to themselves as honest individuals laboring to establish the truth. Others wanted nothing less than to destroy once and for all the connection between science and religion. And those who were politically motivated wanted to bury forever the notion of the divine right of kings. If the scientific evidence denied the truth of the Bible, then it also denied any connection between God and the Monarchy, thus freeing Parliament and the people to redefine the political equations.

So science, its methods and its scope, in the formative beginnings, was very much a creature of the times, unabashedly enlisted in the service of political causes by those who sought to affect political and social developments in their own favor ..."

(cont'd)
Chris_Reeve
1 / 5 (2) Sep 14, 2017
(cont'd)

"It is in this context that we must view the formation and growth of the London Geological Society and its vast influence on the parameters within which geology was to develop into a respectable science ...

The Society grew powerful: it was able to prevent publication of material favorable to catastrophism, and to arrange evidence so as to satisfy a uniformitarian view. Similarly, the political battle was won by the liberals, and the power flow between the King, the Parliament, and the People changed direction ...

It is unfortunate that these crusty notions have shaped the present dilemma of geology. The political issues were settled long ago, but geology is still committed to a paradigm established primarily as part of a political front that is no longer relevant ..."

(cont'd)
Chris_Reeve
1 / 5 (2) Sep 14, 2017
(cont'd)

"It is also unfortunate that catastrophism is linked to biblical fundamentalism because that association has inhibited the evolution of catastrophism as a legitimate avenue of scientific inquiry, without reference to religion or politics ...

Religion may have needed, or may still need catastrophes, but catastrophism doesn't Religion ...

The arguments against the occurrence of global catastrophe as the source of ancient stories about such events have carried the day, at least in part, because of the historical influences on our interpretation of knowledge. After generations of formal education, the bedrock status of this view -- that ancient testimony of world disaster is not to be taken literally -- is so firmly engrained in the sciences that the alternate possibility is almost completely ignored ..."
Maggnus
3 / 5 (2) Sep 14, 2017
What is Uniformitarianism and how did it get here?
Alex Marton

"... the truth of the Biblical story was directly connected to a highly political issue: the legitimacy of the Monarchy ...

In 1807, a small group of amateurs had formed the London Geological Society. In the words of one of its founders, they were starting 'a little talking geological dinner club.' Of the original group of thirteen, four were doctors, two booksellers, one an ex-minister, two amateur chemists who were also independently wealthy, and so on. Only one member had training in geology, but did not pursue it as a livelihood. In fact, an amazing aspect of the London Geological Society is that none of its founders were geologists experienced in or prepared to do field work, but gentlemen inclined to meet for dinner and talk ..."

(cont'd)


Gish-gallop
Maggnus
3 / 5 (2) Sep 14, 2017
(cont'd)

"Even so, in its second year, the London Geological Society was joined by two dozen Fellows of the Royal Society. Its growth accelerated so much that within ten years, its membership was in excess of 400; in 1825, the year of its incorporation, it was up to more than 630. Though England was going through a busy period of canal building and mine exploration (so that there was plenty of digging going on), the number of active geologists who were members of the London Geological Society was very close to zero. The amateurs who were members were interested in geology not so much because of its practical applications or even for the theoretical speculations of a new science, but because of the religious and political consequences it might have.

In the 18th century, the winds of democracy from America and the attacks of thinkers like Locke and Rousseau, among others, questioned the Monarchy as the natural form of government ..."

(cont'd)


Gish-gallop
Maggnus
3 / 5 (2) Sep 15, 2017
(cont'd)

"It is in this context that we must view the formation and growth of the London Geological Society and its vast influence on the parameters within which geology was to develop into a respectable science ...

The Society grew powerful: it was able to prevent publication of material favorable to catastrophism, and to arrange evidence so as to satisfy a uniformitarian view. Similarly, the political battle was won by the liberals, and the power flow between the King, the Parliament, and the People changed direction ...

It is unfortunate that these crusty notions have shaped the present dilemma of geology. The political issues were settled long ago, but geology is still committed to a paradigm established primarily as part of a political front that is no longer relevant ..."

(cont'd)


Gish-gallop.
Maggnus
3 / 5 (2) Sep 15, 2017
(cont'd)

"Many scientists who were also religious tried to find solutions acceptable to the churches, to the people who were increasingly confused, and to themselves as honest individuals laboring to establish the truth. Others wanted nothing less than to destroy once and for all the connection between science and religion. And those who were politically motivated wanted to bury forever the notion of the divine right of kings. If the scientific evidence denied the truth of the Bible, then it also denied any connection between God and the Monarchy, thus freeing Parliament and the people to redefine the political equations.

So science, its methods and its scope, in the formative beginnings, was very much a creature of the times, unabashedly enlisted in the service of political causes by those who sought to affect political and social developments in their own favor ..."

(cont'd)


Gish-gallop
Chris_Reeve
1 / 5 (2) Sep 15, 2017
Please get back to us when you actually have something meaningful to contribute.
Maggnus
5 / 5 (1) Sep 15, 2017
Please get back to us when you actually have something meaningful to contribute.


Back atcha Acolyte. Let me know, please, when you can formulate your very own ideas and articulate them in a manner that allows one to see that you are more than a spout of supra-pantheotic bullshit.
Captain Stumpy
not rated yet Sep 15, 2017
Please get back to us when you actually have something meaningful to contribute.
@idiot f*cktard gish-gallop queen of the eu acolytes

considering you just posted "What is Uniformitarianism and how did it get here?" ans you're making assumptions about facts not topical, present or evident, then everyone could say the same to you

more to the point: Science isn't a debate about the philosophy of belief or why you're too f*cking stupid to comprehend that validated experimentation trumps eu philosophy points
(example: magnetic reconnection - 100K experiments PLUS and counting validating from multiple labs full of electrical engineers and experimental physicists, but the eu doesn't accept the evidence)

.

so until you can present an argument based upon verifiable evidence and science (not eu pseudoscience or arguments of "but once religion ruled the world"....) then your argument is irrelevant

IOW - learn science or STFU

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