Featured Research

from universities, journals, and other organizations

Interpreting Images Of Earth's Interior

Date:
December 15, 1999
Source:
University Of Michigan
Summary:
University of Michigan researchers unveiled a model that relates seismic velocity differences to properties of the mantle.

SAN FRANCISCO --- Over the last two decades, scientists have generated many pictures of Earth's interior by mapping the behavior of seismic waves, those waves of energy that shake the ground during earthquakes. These seismic images show some areas where waves travel faster than average and some where they travel more slowly through the mantle---a plastic-like layer between Earth's crust and core that flows under pressure, lifting or lowering features on the surface.

Interpreting exactly what such differences in "seismic velocity" mean has been a challenge, says Carolina Lithgow-Bertelloni, assistant professor of geological sciences at the University of Michigan. But such understanding is essential to knowing "how the mantle has evolved, how it works dynamically, and what we would expect to happen at Earth's surface as a result," she explains.

In an invited presentation to the American Geophysical Union today, Lithgow-Bertelloni and Lars Stixrude, U-M assistant professor of geological sciences, unveiled a model that relates seismic velocity differences to properties of the mantle. Previous models had assumed that the speed at which seismic waves travel through a particular region in the mantle depends only on the temperature of that region. But Lithgow-Bertelloni and Stixrude reasoned that other factors, such as chemical composition and physical structure of the minerals in the region also contribute.

Preliminary results of work based on their model show that phase transitions---changes in the crystal structure of minerals that result from pressure and temperature changes inside Earth---can suddenly speed up or slow down plate movement at Earth's surface. Such plate movement causes mountain-building, earthquakes and volcanoes.

"While this is a new and exciting result, even more surprising is the fact that when we converted the velocity differences of some seismic models to temperature, the results suggested temperatures high enough to cause melting in some regions of the Earth," says Lithgow-Bertelloni. "One such region that we found down to a depth of 200-600 km is right under the East African rift and might possibly be the source of the volcanism in the area." The next step will be to learn how much of the material has melted and to determine its composition, she adds. Comparing its composition to rocks at the surface will help confirm that the melting is responsible for the volcanic activity.


Story Source:

The above story is based on materials provided by University Of Michigan. Note: Materials may be edited for content and length.


Cite This Page:

University Of Michigan. "Interpreting Images Of Earth's Interior." ScienceDaily. ScienceDaily, 15 December 1999. <www.sciencedaily.com/releases/1999/12/991214113030.htm>.
University Of Michigan. (1999, December 15). Interpreting Images Of Earth's Interior. ScienceDaily. Retrieved October 20, 2014 from www.sciencedaily.com/releases/1999/12/991214113030.htm
University Of Michigan. "Interpreting Images Of Earth's Interior." ScienceDaily. www.sciencedaily.com/releases/1999/12/991214113030.htm (accessed October 20, 2014).

Share This



More Earth & Climate News

Monday, October 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Powerful Hurricane Gonzalo Heads to Bermuda

Raw: Powerful Hurricane Gonzalo Heads to Bermuda

AP (Oct. 17, 2014) Hurricane Gonzalo pounded Bermuda with wind and heavy surf on Friday, bearing down on the tiny British territory as a powerful Category 3 storm that could raise coastal seas as much as 10 feet. (Oct. 17) Video provided by AP
Powered by NewsLook.com
So, Kangaroos Didn't Always Hop

So, Kangaroos Didn't Always Hop

Newsy (Oct. 16, 2014) Researchers believe an extinct kangaroo species weighed 500 pounds or more and couldn't hop. Video provided by Newsy
Powered by NewsLook.com
Hurricane Gonzalo Is A Category 4 And Heading To Bermuda

Hurricane Gonzalo Is A Category 4 And Heading To Bermuda

Newsy (Oct. 16, 2014) Powerful hurricane could hit Bermuda this weekend, and even if it misses it will likely do some damage. Video provided by Newsy
Powered by NewsLook.com
The Largest Volcano In Centuries Is Spewing Toxic Gas

The Largest Volcano In Centuries Is Spewing Toxic Gas

Newsy (Oct. 16, 2014) One of the largest volcanic eruptions in centuries is occurring on Iceland. The volcano Bardarbunga is producing high levels of sulfur dioxide. 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