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| Satellite data show gravity change after 2004 tsunami | | |
Jakarta, Aug 09: Scientists funded by NASA, the US national science foundation and the Ohio supercomputer centre have used satellite data for the first time to detect changes in the earth's surface caused by a massive earthquake.
The discovery signifies a new use for the data from NASA's two gravity recovery and climate experiment (grace) satellites and might offer a new approach to understanding how earthquakes work, a release from Ohio state university said.
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 that 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 seafloor. The slippage occurred along 1,207 kilometers 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 kilometers.
"The earthquake changed the gravity in that part of the world in two ways that we were able to detect," said Shin-Chan Han, a research scientist in the Osu School of Earth Sciences.
First, he said, the quake triggered the massive uplift of the seafloor, changing the geometry of the region and altering previous Global Positioning System (GPS) satellite measurements from the area.
Second, the density of the rock under the seafloor was changed after the slippage, and an increase or decrease in density produces a detectable gravity change, Han said.
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