Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Minerals are key to earthquakes deep in the Earth

01.04.2004


A team of geologists can tell you more about earthquakes in "Middle Earth" than can the whole trilogy of "The Lord of the Rings."



Specifically, how do earthquakes happen in Earth’s tightly squeezed middle layers where pressure is far too great to allow any shifting of the rock? According to a paper published in the April 1 issue of the journal Nature, breakdown of the mineral serpentine provides enough wiggle room to trigger an earthquake. The report suggests a new mechanism to explain how quakes can occur at such depths.

"This exciting work addresses the central question of how large earthquakes can be generated in deep subduction zones," said Robin Reichlin, program director in the National Science Foundation (NSF) division of earth sciences, which funded the research. "This has been a much-debated topic, and this work goes a long way toward showing that dehydration of minerals plays an important role in this process."


Haemyeong Jung, Harry W. Green II and Larissa Dobrzhinetskaya of the University of California at Riverside, point out that while it is impossible to break anything by normal brittle fracture at pressures higher than those found at only a few 10s of kilometers (km) deep, earthquakes occur continuously at depths close to 700 km.

What is the explanation of this paradox?

A mechanism called "dehydration embrittlement" breaks down the mineral serpentine, to form the mineral olivine, accompanied by the release of water. That water can assist brittle failure at high pressure, but how? Green explains that before now, scientists have expected faulting instability only if the volume change during serpentine breakdown is positive.

In their article, the team reports experiments conducted between 10,000 and 60,000 times the pressure of the atmosphere at sea level, corresponding to depths in the earth of 30-190 km. Over that pressure range, the volume upon dehydration of serpentine changes from strongly positive to markedly negative, yet the faulting instability remains.

The microstructures preserved in the rocks after faulting provide insight into why this is so. The results confirm that earthquakes can be triggered by serpentine breakdown down to depths of as much as 250 km.

"I am becoming more and more convinced that mineral reactions also are involved in triggering shallow earthquakes such as those that threaten California," Green said. "Our hope is that we learn more about the thing we know least about, the initiation part of these earthquakes, how they get started. This is what we are trying to understand."


Additional Contacts:
NSF Program Contact: Robin Reichlin, rreichli@nsf.gov, 703-292-8550
UC-RiversideContact: Kris Lovekin, kris.lovekin@ucr.edu, 909-787-2495

NSF is an independent federal agency that supports fundamental research and education across all fields of science and engineering, with an annual budget of nearly $5.58 billion. NSF funds reach all 50 states through grants to nearly 2,000 universities and institutions. Each year, NSF receives about 40,000 competitive requests for funding, and makes about 11,000 new funding awards. NSF also awards over $200 million in professional and service contracts yearly.

Receive official NSF news electronically through the e-mail delivery system, NSFnews. To subscribe, send an e-mail message to join-nsfnews@lists.nsf.gov. In the body of the message, type "subscribe nsfnews" and then type your name. (Ex.: "subscribe nsfnews John Smith")

Cheryl Dybas | NSF
Further information:
http://www.nsf.gov
http://www.nsf.gov/od/lpa/news/media/start.htm

More articles from Earth Sciences:

nachricht Abrupt cloud clearing events over southeast Atlantic Ocean are new piece in climate puzzle
23.07.2018 | University of Kansas

nachricht Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Detecting damage in non-magnetic steel with the help of magnetism

23.07.2018 | Materials Sciences

Researchers move closer to completely optical artificial neural network

23.07.2018 | Information Technology

Enabling technology in cell-based therapies: Scale-up, scale-out or program in-place

23.07.2018 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>