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 'Quartz' crystals at the Earth's core power its magnetic field
23.02.2017 | Tokyo Institute of Technology

nachricht NASA spies Tropical Cyclone 08P's formation
23.02.2017 | 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: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

From rocks in Colorado, evidence of a 'chaotic solar system'

23.02.2017 | Physics and Astronomy

'Quartz' crystals at the Earth's core power its magnetic field

23.02.2017 | Earth Sciences

Antimicrobial substances identified in Komodo dragon blood

23.02.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>