Featured Research

from universities, journals, and other organizations

Breakthrough achieved in explaining why tectonic plates move the way they do

Date:
July 17, 2010
Source:
University of California - San Diego
Summary:
Geophysicists have developed a new theory to explain the global motions of tectonic plates on the earth's surface. The new theory extends the theory of plate tectonics -- a kinematic description of plate motion without reference to the forces behind it -- with a dynamical theory that provides a physical explanation for both the motions of tectonic plates as well as motion of plate boundaries.

The sinking of the Farallon plate beneath the North American continent over 30 million years created the geologic feature known as the Basin and Range Province, an area of the western United States that encompasses much of Nevada, seen here in a topographic model.
Credit: Mike Sandiford/University of Melbourne

A team of researchers including Scripps Institution of Oceanography, UC San Diego geophysicist Dave Stegman has developed a new theory to explain the global motions of tectonic plates on the earth's surface.

Related Articles


The new theory extends the theory of plate tectonics -- a kinematic description of plate motion without reference to the forces behind it -- with a dynamical theory that provides a physical explanation for both the motions of tectonic plates as well as motion of plate boundaries. The new findings have implications for how scientists understand the geological evolution of Earth, and in particular, the tectonic evolution of western North America, in the past 50 million years.

The research, led by Monash University's Wouter Schellart, is published in the July 16 issue of the journal Science.

These findings provide a new explanation as to why tectonic plates move along the Earth's surface at the speeds that are observed, the details of which were previously not well-understood.

"The earth's surface is covered with tectonic plates that move with respect to one another at centimeters per year," Schellart said. "These plates converge at deep-sea trenches, plate boundaries where one plate sinks (subducts) below the other at so-called subduction zones. The velocities of these plates and the velocities of the boundaries between these plates vary significantly on Earth."

Schellart and his team, including Stegman and Rebecca Farrington, Justin Freeman and Louis Moresi from Monash University, used observational data and advanced computer models to develop a new mathematical scaling theory, which demonstrates that the velocities of the plates and the plate boundaries depend on the size of subduction zones and the presence of subduction zone edges.

"The scalings for how subducted plates sink in the earth's mantle are based on essentially the same fluid dynamics that describe how a penny sinks through a jar of honey," said Stegman, who developed the computer models that helped the team reenact tens of millions of years of tectonic movement. "The computer models demonstrate that the subducted portion of a tectonic plate pulls on the portion of the plate that remains on the earth's surface. This pull results in either the motion of the plate, or the motion of the plate boundary, with the size of the subduction zone determining how much of each."

"In some ways, plate tectonics is the surface expression of dynamics in the earth's interior but now we understand the plates themselves are controlling the process more than the mantle underneath. It means Earth is really more of a top-down system than the predominantly held view that plate motion is being driven from the bottom-up."

This discovery explains why the Australian, Nazca and Pacific plates move up to four times faster than the smaller African, Eurasian and Juan de Fuca plates.

"It also provides explanations for the motions of the ancient Farallon plate that sank into the mantle below North and South America. This plate slowed down during eastward motion from about 10 centimeters (four inches) per year some 50 million years ago to only 2 centimeters (0.8 inches) per year at present," Schellart said.

The decrease in plate velocity resulted from the decrease in subduction zone size, which decreased from 14,000 kilometers (8,700 miles) to only 1,400 kilometers (870 miles).

"This had a dramatic effect on the topography and the structure of the North American continent," said Schellart. "Until 50 million years ago, the west coast of North America was characterized by a massive mountain chain similar to the present day Andes in South America, and ran from Canada in the north to southern Mexico in the south."

As the subduction zone decreased in size, the compressive stresses along the west coast of North America decreased, resulting in destruction of the mountain range and formation of the Basin and Range province, a 2 million-square-kilometer (772,000-square-mile) area of elongated basins and ridges that characterizes the present-day western North American landscape.


Story Source:

The above story is based on materials provided by University of California - San Diego. Note: Materials may be edited for content and length.


Journal Reference:

  1. W. P. Schellart, D. R. Stegman, R. J. Farrington, J. Freeman, and L. Moresi. Cenozoic Tectonics of Western North America Controlled by Evolving Width of Farallon Slab. Science, 16 July 2010: Vol. 329. no. 5989, pp. 316 - 319 DOI: 10.1126/science.1190366

Cite This Page:

University of California - San Diego. "Breakthrough achieved in explaining why tectonic plates move the way they do." ScienceDaily. ScienceDaily, 17 July 2010. <www.sciencedaily.com/releases/2010/07/100716125841.htm>.
University of California - San Diego. (2010, July 17). Breakthrough achieved in explaining why tectonic plates move the way they do. ScienceDaily. Retrieved October 25, 2014 from www.sciencedaily.com/releases/2010/07/100716125841.htm
University of California - San Diego. "Breakthrough achieved in explaining why tectonic plates move the way they do." ScienceDaily. www.sciencedaily.com/releases/2010/07/100716125841.htm (accessed October 25, 2014).

Share This



More Earth & Climate News

Saturday, October 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

EU Gets Climate Deal, UK PM Gets Knock

EU Gets Climate Deal, UK PM Gets Knock

Reuters - Business Video Online (Oct. 24, 2014) EU leaders achieve a show of unity by striking a compromise deal on carbon emissions. But David Cameron's bid to push back EU budget contributions gets a slap in the face as the European Commission demands an extra 2bn euros. David Pollard reports. Video provided by Reuters
Powered by NewsLook.com
Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Reuters - Innovations Video Online (Oct. 24, 2014) Miniature deep sea animals discovered off the Australian coast almost three decades ago are puzzling scientists, who say the organisms have proved impossible to categorise. Academics at the Natural History of Denmark have appealed to the world scientific community for help, saying that further information on Dendrogramma enigmatica and Dendrogramma discoides could answer key evolutionary questions. Jim Drury has more. Video provided by Reuters
Powered by NewsLook.com
Raw: Tornado Rips Roofs in Washington State

Raw: Tornado Rips Roofs in Washington State

AP (Oct. 24, 2014) A rare tornado ripped roofs off buildings, uprooted trees and shattered windows Thursday afternoon in the southwest Washington city of Longview, but there were no reports of injuries. (Oct. 24) Video provided by AP
Powered by NewsLook.com
Fast-Moving Lava Headed For Town On Hawaii's Big Island

Fast-Moving Lava Headed For Town On Hawaii's Big Island

Newsy (Oct. 24, 2014) Lava from the Kilauea volcano on Hawaii's Big Island has accelerated as it travels toward a town called Pahoa. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins