Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Earthquakes reveal deep secrets beneath East Asia

15.05.2015

XSEDE Campus Champions, Stampede and Lonestar4 supercomputers of TACC help create 3-D images deep underground

A new work based on 3-D supercomputer simulations of earthquake data has found hidden rock structures deep under East Asia. Researchers from China, Canada, and the U.S. worked together to publish their results in March 2015 in the American Geophysical Union Journal of Geophysical Research, Solid Earth.


Three-dimensional high velocity structures beneath East Asia from 50 km to 1000 km depth viewed from the southeast. Surface topography with vertical exaggeration is superimposed for geographic references. Isosurfaces of high velocity anomalies in percent referenced to a one-dimensional earth model (STW105) at each depth are plotted from 1% to 4% with 1% interval. Three cut planes show shear wave velocity maps at 410 km, 660 km, and 1000 km depths. The highest elevations represent the Himalayas and the Tibetan Plateau.

Credit: Min Chen, Rice University

The scientists used seismic data from 227 East Asia earthquakes during 2007-2011, which they used to image depths to about 900 kilometers, or about 560 miles below ground.

Notable structures include a high velocity colossus beneath the Tibetan plateau, and a deep mantle upwelling beneath the Hangai Dome in Mongolia. The researchers say their line of work could potentially help find hidden hydrocarbon resources, and more broadly it could help explore the Earth under East Asia and the rest of the world.

"With the help of supercomputing, it becomes possible to render crystal-clear images of Earth's complex interior," principal investigator and lead author Min Chen said of the study. Chen is a postdoctoral research associate in the department of Earth Sciences at Rice University.

Chen and her colleagues ran simulations on the Stampede and Lonestar4 supercomputers of the Texas Advanced Computing Center through an allocation by XSEDE, the eXtreme Science and Engineering Discovery Environment funded by the National Science Foundation.

"We are combining different kinds of seismic waves to render a more coherent image of the Earth," Chen said. "This process has been helped by supercomputing power that is provided by XSEDE."

"What is really new here is that this is an application of what is sometimes referred to as full waveform inversion in exploration geophysics," study co-author Jeroen Tromp said. Tromp is a professor of Geosciences and Applied and Computational Mathematics, and the Blair Professor of Geology at Princeton University.

In essence the application combined seismic records from thousands of stations for each earthquake to produce scientifically accurate, high-res 3-D tomographic images of the subsurface beneath immense geological formations.

XSEDE provided more than just time on supercomputers for the science team. Through the Campus Champions program, researchers worked directly with Rice XSEDE champion Qiyou Jiang of Rice's Center for Research Computing and with former Rice staffer Roger Moye, who used Rice's DAVinCI supercomputer to help Chen with different issues she had with high performance computing." "They are the contacts I had with XSEDE," Chen said.

"These collaborations are really important," said Tromp of XSEDE. "They cannot be done without the help and advice of the computational science experts at these supercomputing centers. Without access to these computational resources, we would not be able to do this kind of work."

Like a thrown pebble generates ripples in a pond, earthquakes make waves that can travel thousands of miles through the Earth. A seismic wave slows down or speeds up a small percentage as it travels through changes in rock composition and temperature. The scientists mapped these wave speed changes to model the physical properties of rock hidden below ground.

Tromp explained that the goal for his team was to match the observed ground-shaking information at seismographic stations to fully numerical simulations run on supercomputers.

"In the computer, we set off these earthquakes," says Tromp. "The waves ripple across southeast Asia. We simulate what the ground motion should look like at these stations. Then we compare that to the actual observations.

The differences between our simulations and the observations are used to improve our models of the Earth's interior," Tromp said. "What's astonishing is how well those images correlate with what we know about the tectonics, in this case, of East Asia from surface observations."

The Tibetan Plateau, known as 'the roof of the world,' rises about three miles, or five kilometers above sea level. The details of how it formed remain hidden to scientists today.

The leading theory holds that the plateau formed and is maintained by the northward motion of the India plate, which forces the plateau to shorten horizontally and move upward simultaneously.

Scientists can't yet totally account for the speed of the movement of ground below the surface at the Tibetan Plateau or what happened to the Tethys Ocean that once separated the India and Eurasia plates. But a piece of the puzzle might have been found.

"We found that beneath the Tibetan plateau, the world's largest and highest plateau, there is a sub-vertical high velocity structure that extends down to the bottom of the mantle transition zone," Chen said.

The bottom of the transition zone goes to depths of 660 kilometers, she said. "Three-dimensional geometry of the high velocity structure depicts the lithosphere beneath the plateau, which gives clues of the fate of the subducted oceanic and the continental parts of the Indian plate under the Eurasian plate," Chen said.

The collision of plates at the Tibetan Plateau has caused devastating earthquakes, such as the recent 2015 Nepal earthquake at the southern edge of where the two plates meet. Scientists hope to use earthquakes to model the substructure and better understand the origins of these earthquakes.

To reach any kind of understanding, the scientists first grappled with some big data, 1.7 million frequency-dependent traveltime measurements from seismic waveforms. "We applied this very sophisticated imaging technique called adjoint tomography with a key component that is a numerical code package called SPECFEM3D_GLOBE," Chen said.

Specifically, they used SPECFEM3D GLOBE, open source software maintained by the UC Davis Computational Infrastructure for Geodynamics. "It uses parallel computing to simulate the very complex seismic waves through the Earth," Chen said.

Even with the tools in place, the study was still costly. "The cost is in the simulations of the wave propagation," says Tromp. "That takes hundreds of cores for tens of minutes at a time per earthquake.

As you can imagine, that's a very expensive proposition just for one iteration simulating all these 227 earthquakes." In all, the study used about eight million CPU hours on the Stampede and Lonestar4 supercomputers.

"The big computing power of supercomputers really helped a lot in terms of shortening the simulation time and in getting an image of the Earth within a reasonable timeframe," said Chen. "It's still very challenging. It took us two years to develop this current model beneath East Asia. Hopefully, in the future it's going to be even faster."

Three-D imaging inside the Earth can help society find new resources, said Tromp. The iterative inversion methods they used to model structures deep below are the same ones used in exploration seismology to look for hidden hydrocarbons.

"There's a wonderful synergy at the moment," Tromp said. "The kinds of things we're doing here with earthquakes to try and image the Earth's crust and upper mantle and what people are doing in exploration geophysics to try and image hydrocarbon reservoirs."

"In my point of view, it's the era of big seismic data," Chen said. She said their ultimate goal is to make everything about seismic imaging methods automatic and accessible by anyone to better understand the Earth.

It sounded something like a Google Earth for inside the Earth itself. "Right, exactly. Assisted by the supercomputing systems of XSEDE, you can have a tour inside the Earth and possibly make some new discoveries." Chen said.

###

The science team for this study included Min Chen and Fenglin Niu of Rice University; Qinya Liu of the University of Toronto; Jeroen Tromp of Princeton University; and Xiufen Zheng of the Institute of Geophysics, China Earthquake Administration, Beijing, China. The National Science Foundation (US) provided the study funding.

The DAVinCI supercomputer is administered by Rice's Ken Kennedy Institute for Information Technology and supported by the National Science Foundation. The researchers also thank Kiran Thyagaraja, Franco Bladilo, and Kim Andrews for their assistance with work on DAVinCI.

Media Contact

Jorge Salazar
jorge@tacc.utexas.edu
512-471-3980

http://www.tacc.utexas.edu/ 

Jorge Salazar | EurekAlert!

More articles from Earth Sciences:

nachricht New plate adds plot twist to ancient tectonic tale
15.08.2017 | Rice University

nachricht Global warming will leave different fingerprints on global subtropical anticyclones
14.08.2017 | Institute of Atmospheric Physics, Chinese Academy of Sciences

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

Im Focus: Scientists improve forecast of increasing hazard on Ecuadorian volcano

Researchers from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, the Italian Space Agency (ASI), and the Instituto Geofisico--Escuela Politecnica Nacional (IGEPN) of Ecuador, showed an increasing volcanic danger on Cotopaxi in Ecuador using a powerful technique known as Interferometric Synthetic Aperture Radar (InSAR).

The Andes region in which Cotopaxi volcano is located is known to contain some of the world's most serious volcanic hazard. A mid- to large-size eruption has...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

New thruster design increases efficiency for future spaceflight

16.08.2017 | Physics and Astronomy

Transporting spin: A graphene and boron nitride heterostructure creates large spin signals

16.08.2017 | Materials Sciences

A new method for the 3-D printing of living tissues

16.08.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>