Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

U. of Colorado geophysicists image rock layers under Himalaya

30.06.2005


New technique developed to visualize colliding rock bodies



A team of geophysicists at the University of Colorado at Boulder has developed a new technique to visualize the colliding rock bodies beneath the Himalaya with unprecedented detail, answering a number of questions about the world’s highest mountains and providing a new tool for assessing earthquake hazards.

The study, "Imaging the Indian Subcontinent Beneath the Himalaya" appears in the June 30 issue of the journal Nature. Anne Sheehan, Roger Bilham, Vera Schulte-Pelkum and Gaspar Monsalve of CU-Boulder’s Cooperative Institute for Research in Environmental Sciences and department of geological sciences worked on the project along with scientists from the State University of New York at Binghamton and Kathmandu, Nepal.


"We imaged the boundary between the Indian and Asian tectonic plates by developing a new technique that highlights strongly deformed rocks beneath Earth’s surface, and applied it to data we collected with a network of temporary seismic sensors deployed in Nepal and Tibet," said Schulte-Pelkum, the paper’s lead author and a CIRES researcher.

The network included 29 broadband seismometers operated by the CU-Boulder and SUNY Binghamton teams. About 1,700 earthquakes from as far away as Europe, Alaska and Japan were recorded during an 18-month period starting in 2001. The study was funded primarily by the National Science Foundation.

"Our images of the crust and upper mantle show how the upper Indian crust fragments and is incorporated in the Himalaya, while the lower crust slides under Tibet and undergoes alterations that may help explain how the plateau maintains its high altitude," Schulte-Pelkum said.

Sheehan said Schulte-Pelkum developed a truly novel method to visualize the forces at work underneath the Himalaya. "It’s very exciting, and it’s something we can use elsewhere to analyze shear in the crust."

Shear zones are similar to faults, Schulte-Pelkum said. Faults are brittle structures at or near the surface of the earth, while shear zones are found at depths of 10 miles or more where heat causes more ductile, or flowing, rock movement.

In subduction zones such as where India and Asia collide, however, earthquakes along brittle faults can occur at depth because rock temperatures are cooler, the researchers said.

The collision of India into Asia forms the Himalaya, the world’s highest mountain chain, and Tibet, the world’s largest high plateau, Schulte-Pelkum explained. "From surface geology, we know that India dives under Asia. In Nepal, this slip is expressed in very large, destructive earthquakes that occur somewhere along the base of the mountains a few times a century."

However, the infrequency of the tremors had left scientists with few clues as to the structure of the region. "During the interval between these earthquakes, the shallow fault between underthrusting India and overriding Asia is seismically quiet and difficult to detect," Schulte-Pelkum said.

Sheehan explained that until now, geophysicists could analyze the movement of rock bodies only on the surface, where deformation can be directly observed.

With the team’s new method, geophysicists can study the deep crust and determine the direction rocks are being sheared. The shearing is similar to a deck of cards being spread out on a table, Sheehan explained. "We can see how the deep crust has moved. Seeing where these structures are and how they have moved in the subsurface helps us better understand where local hazards are.

"If we can more accurately calculate the subsurface geometries, we can improve our estimations of how the ground will shake during an earthquake. We can’t predict earthquakes, but we can get a better idea of how an earthquake’s energy will radiate," said Sheehan, an associate professor of geological sciences at CU-Boulder and a CIRES researcher.

"The Los Angeles Basin has all sorts of folds and faults and subsurface shear, so it would be another potential place to apply some of these techniques to get high-resolution images," Sheehan said.

Vera Schulte-Pelkum | EurekAlert!
Further information:
http://www.colorado.edu

More articles from Earth Sciences:

nachricht Mountain glaciers shrinking across the West
23.10.2017 | University of Washington

nachricht Climate change weakens Walker circulation
20.10.2017 | MARUM - Zentrum für Marine Umweltwissenschaften an der Universität Bremen

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Salmonella as a tumour medication

HZI researchers developed a bacterial strain that can be used in cancer therapy

Salmonellae are dangerous pathogens that enter the body via contaminated food and can cause severe infections. But these bacteria are also known to target...

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

3rd Symposium on Driving Simulation

23.10.2017 | Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

 
Latest News

Microfluidics probe 'cholesterol' of the oil industry

23.10.2017 | Life Sciences

Gamma rays will reach beyond the limits of light

23.10.2017 | Physics and Astronomy

The end of pneumonia? New vaccine offers hope

23.10.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>