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

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Researchers shoot for success with simulations of laser pulse-material interactions

29.03.2017 | Materials Sciences

Igniting a solar flare in the corona with lower-atmosphere kindling

29.03.2017 | Physics and Astronomy

As sea level rises, much of Honolulu and Waikiki vulnerable to groundwater inundation

29.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>