Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Satellite data reveals gravity change from Sumatran earthquake

07.08.2006
For the first time, scientists have been able to use satellite data to detect the changes in the earth's surface caused by a massive earthquake.

The discovery, reported in the latest issue of the journal Science, signifies a new use for the data from NASA's two GRACE satellites and offers a possible new approach to understanding how earthquakes work.

The research paints a clearer picture of how the earth changed after the December, 2004 Sumatra-Andaman earthquake, the 9.1-magnitude temblor in the Indian Ocean which caused a deadly tsunami killing nearly 230,000 and displacing more than 1 million people.

Centered off the west coast of northern Sumatra, the event followed the slipping of two continental plates along a massive fault under the sea floor. The slippage occurred along 750 miles of the line where the Indian plate slides under the Burma plate, a process called subduction. The quake raised the seafloor in the region by several meters for thousands of square miles.

“The earthquake changed the gravity in that part of the world in two ways that we were able to detect,” explained Shin-Chan Han, a research scientist in the School of Earth Sciences at Ohio State .

First, he said, the quake triggered the massive uplift of the seafloor, changing the geometry of the region and altering previous GPS (global positioning satellite) measurements from the area. Those changes were detectable by GRACE's instruments.

And second, the density of the rock beneath the seafloor was changed after the slippage, and an increase or decrease in density produces a detectable gravity change, Han said.

The GRACE (Gravity Recovery and Climate Experiment) satellites were launched in 2002 and have been gathering global gravity measurements ever since. The identical instruments orbit some 186 to 310 miles (300 to 500 kilometers) above the planet's surface and fly 136 miles (220 kilometers) apart.

The satellites can detect changes in the density of the earth's crust, or in GPS measurements on the ground, and that can now signal changes in the planet's gravity at that point.

Along with colleagues C.K. Shum and Michael Bevis, both professors in the School of Earth Sciences, Han assembled several years of data covering the Indian Ocean region and filtered out seasonal variations. The changing flow of the massive Mekong River, for example, affects gravity measurements for the area and these annual shifts must be removed from the data to detect changes caused by a quake.

The researchers then plugged the data into the latest seismic computer model which painted a picture of gravity increases on one side of the fault line and decreases on the other.

“With this seismic model we were able to explain and interpret the GRACE observations,” Han said, adding that earthquake models are still evolving. “But the observations can also be used to validate the quality of the model itself and therefore improve our knowledge about the solid earth's dynamics.”

The detection of such quakes comes only after extensive data analysis. Real-time detection is far off in the future – if possible at all. And currently, this GRACE technique was applied to understand the mechanism of “great” earthquakes – those exceeding magnitude 9 – which are very rare events.

Detecting “major” quakes – those measuring a magnitude of 7 to 8.9 – which occur frequently is being investigated. NASA's planned extension of the current mission, dubbed GRACE 2, and its enhanced instrumentation should aid in that effort.

However, Han is hopeful that NASA's planned expansion of the current mission, dubbed GRACE 2, and its enhanced instrumentation, might allow the detection of “major” quakes – those measuring a magnitude 7 to 8.9 – which occur frequently.

Chung-Yen Kuo, a post-doctoral researcher in the School of Earth Sciences at Ohio State , and Chen Ji, an assistant professor of earth science at the University of California, Santa Barbara , both participated in the study. Support for this research came from the National Aeronautics Space Administration, the National Science Foundation and the Ohio Supercomputer Center.

Shin-Chan Han | EurekAlert!
Further information:
http://www.osu.edu

More articles from Earth Sciences:

nachricht NASA examines Peru's deadly rainfall
24.03.2017 | NASA/Goddard Space Flight Center

nachricht Steep rise of the Bernese Alps
24.03.2017 | Universität Bern

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

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...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

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

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>