Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Seismic study reveals huge amount of water dragged into Earth's interior

18.12.2018

Slow-motion collisions of tectonic plates under the ocean drag water into the deep Earth

Slow-motion collisions of tectonic plates under the ocean drag about three times more water down into the deep Earth than previously estimated, according to a first-of-its-kind seismic study that spans the Mariana Trench, a crescent-shaped trench in the Western Pacific that measures 1,500 miles long and is the deepest ocean trench in the world.


This is recovery of seismographs on uninhabited islands in the Commonwealth of the Northern Mariana Islands.

Credit: Douglas Wiens


This is the deployment of an ocean bottom seismograph from the research vessel Thompson.

Credit: Douglas Weins

The observations from the trench have important implications for the global water cycle, according to researchers at Washington University in St. Louis whose work is supported by the National Science Foundation (NSF).

"People knew that subduction zones could bring down water, but they didn't know how much water," said Chen Cai, lead author of the study, which was published in this week's issue of the journal Nature.

"This research shows that subduction zones move far more water into Earth's deep interior -- many miles below the surface -- than previously thought," said Candace Major, a program director in NSF's Division of Ocean Sciences. "The results highlight the important role of subduction zones in Earth's water cycle."

Researchers listened to more than a year's worth of Earth's rumblings, from ambient noise to actual earthquakes, using a network of 19 ocean-bottom seismographs deployed across the Mariana Trench, along with seven island-based seismographs.

"Previous estimates vary widely on the amount of water that is subducted deeper than 60 miles," said Doug Wiens, a geoscientist at Washington University and co-author of the paper. "The main source of uncertainty in these calculations was the initial water content of the subducting uppermost mantle."

The Mariana Trench is where the western Pacific Ocean plate slides beneath the Mariana Plate and sinks deep into the Earth's mantle as the plates slowly converge.

The new seismic observations paint a more detailed picture of the Pacific Plate bending into the trench, resolving its 3D structure and tracking the relative speeds of types of rock that have different capabilities for holding water.

Rock can grab and hold onto water in a variety of ways. Ocean water atop the tectonic plate runs down into the Earth's crust and upper mantle along fault lines that lace the area where the plates collide and bend. Then it gets trapped.

Under certain temperatures and pressure conditions, chemical reactions force the water into a non-liquid form -- hydrous minerals (wet rocks) -- locking the water into the plate. Then the plate continues to crawl ever deeper into the Earth's mantle, ferrying the water with it.

Previous studies at subduction zones like the Mariana Trench have noted that the subducting plate could hold water. But they didn't determine how much water it held or how deep it went.

The seismic images Cai and Wiens obtained show that the area of hydrated rock at the Mariana Trench extends almost 20 miles beneath the seafloor -- much deeper than previously thought.

The amount of water in this block of hydrated rock is considerable, the scientists said.

For the Mariana Trench region alone, four times more water subducts than previously calculated. These results can be extrapolated to predict the conditions in other ocean trenches worldwide.

"If other old, cold subducting slabs contain similarly thick layers of hydrous mantle, then estimates of the global water flux into the mantle at depths greater than 60 miles must be increased by a factor of about three," said Wiens.

For water in the Earth, what goes down must come up. All the water going into the Earth at subduction zones must be coming back up somehow, not continuously piling up inside the Earth.

Scientists believe that most of the water that goes down at a trench comes back into the atmosphere as water vapor when volcanoes erupt. But with the revised estimates of water from the new study, the amount of water going in seems to greatly exceed the amount of water coming out.

"The estimates of water coming back out through the volcanic arc are probably very uncertain," said Wiens, who hopes that this study will encourage other researchers to reconsider their models for how water moves out.

"Does the amount of water vary substantially from one subduction zone to another, based on the kind of faulting where the plate bends?" Wiens asked. "There have been suggestions of that in Alaska and in Central America. But no one has yet looked at deeper structures like we were able to do in the Mariana Trench."

Media Contact

Cheryl Dybas
cdybas@nsf.gov
703-292-7734

 @NSF

http://www.nsf.gov 

Cheryl Dybas | EurekAlert!
Further information:
https://www.nsf.gov/news/news_summ.jsp?cntn_id=297133

More articles from Earth Sciences:

nachricht Upwards with the “bubble shuttle”: How sea floor microbes get involved with methane reduction in the water column
27.05.2020 | Leibniz-Institut für Ostseeforschung Warnemünde

nachricht An international team including scientists from MARUM discovered ongoing and future tropical diversity decline
26.05.2020 | 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: Biotechnology: Triggered by light, a novel way to switch on an enzyme

In living cells, enzymes drive biochemical metabolic processes enabling reactions to take place efficiently. It is this very ability which allows them to be used as catalysts in biotechnology, for example to create chemical products such as pharmaceutics. Researchers now identified an enzyme that, when illuminated with blue light, becomes catalytically active and initiates a reaction that was previously unknown in enzymatics. The study was published in "Nature Communications".

Enzymes: they are the central drivers for biochemical metabolic processes in every living cell, enabling reactions to take place efficiently. It is this very...

Im Focus: New double-contrast technique picks up small tumors on MRI

Early detection of tumors is extremely important in treating cancer. A new technique developed by researchers at the University of California, Davis offers a significant advance in using magnetic resonance imaging to pick out even very small tumors from normal tissue. The work is published May 25 in the journal Nature Nanotechnology.

researchers at the University of California, Davis offers a significant advance in using magnetic resonance imaging to pick out even very small tumors from...

Im Focus: I-call - When microimplants communicate with each other / Innovation driver digitization - "Smart Health“

Microelectronics as a key technology enables numerous innovations in the field of intelligent medical technology. The Fraunhofer Institute for Biomedical Engineering IBMT coordinates the BMBF cooperative project "I-call" realizing the first electronic system for ultrasound-based, safe and interference-resistant data transmission between implants in the human body.

When microelectronic systems are used for medical applications, they have to meet high requirements in terms of biocompatibility, reliability, energy...

Im Focus: When predictions of theoretical chemists become reality

Thomas Heine, Professor of Theoretical Chemistry at TU Dresden, together with his team, first predicted a topological 2D polymer in 2019. Only one year later, an international team led by Italian researchers was able to synthesize these materials and experimentally prove their topological properties. For the renowned journal Nature Materials, this was the occasion to invite Thomas Heine to a News and Views article, which was published this week. Under the title "Making 2D Topological Polymers a reality" Prof. Heine describes how his theory became a reality.

Ultrathin materials are extremely interesting as building blocks for next generation nano electronic devices, as it is much easier to make circuits and other...

Im Focus: Rolling into the deep

Scientists took a leukocyte as the blueprint and developed a microrobot that has the size, shape and moving capabilities of a white blood cell. Simulating a blood vessel in a laboratory setting, they succeeded in magnetically navigating the ball-shaped microroller through this dynamic and dense environment. The drug-delivery vehicle withstood the simulated blood flow, pushing the developments in targeted drug delivery a step further: inside the body, there is no better access route to all tissues and organs than the circulatory system. A robot that could actually travel through this finely woven web would revolutionize the minimally-invasive treatment of illnesses.

A team of scientists from the Max Planck Institute for Intelligent Systems (MPI-IS) in Stuttgart invented a tiny microrobot that resembles a white blood cell...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Dresden Nexus Conference 2020: Same Time, Virtual Format, Registration Opened

19.05.2020 | Event News

Aachen Machine Tool Colloquium AWK'21 will take place on June 10 and 11, 2021

07.04.2020 | Event News

International Coral Reef Symposium in Bremen Postponed by a Year

06.04.2020 | Event News

 
Latest News

Biophysicists reveal how optogenetic tool works

29.05.2020 | Life Sciences

Convenient location of a near-threshold proton-emitting resonance in 11B

29.05.2020 | Physics and Astronomy

Mapping immune cells in brain tumors

29.05.2020 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>