Scientists funded
by NASA, the US National Science Foundation and the
Ohio Supercomputer Centre have used satellite data from
NASA's two gravity recovery and climate experiment (GRACE)
satellites for the first time to detect changes in the
Earth’s surface caused by a massive earthquake.
The research paints a clearer picture of how the Earth
changed after the December 2004 Sumatra-Andaman earthquake,
the 9.1-magnitude temblor that set off a devastating
tsunami across the Indian Ocean in December 2004 disrupted
the earth enough to change gravity and to deflect satellites
passing hundreds of miles above. "The earthquake
changed the gravity in that part of the world in two
ways that we were able to detect," said Shin-Chan
Han, an Ohio State research scientist. First, he said,
the quake triggered the massive uplift of the seafloor,
changing the geometry of the region and altering previous
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. www.zeenews.com |