Satellite found 2011 Japan earthquake left mark on Earth's gravity

Dec. 4, 2013 at 5:57 PM
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PARIS, Dec. 4 (UPI) -- A European satellite that mapped the Earth's gravity has revealed the devastating Japanese earthquake of 2011 left a "scar" on Earth's gravity, scientists say.

The effects of the 9.0 earthquake that struck east of Japan's Honshu Island on March 11, 2011 are clearly visible in data gathered by the European Space Agency's GOCE satellite, an ESA release reported Wednesday.

Large earthquakes not only deform Earth's crust, ESA scientists said, but can also cause tiny changes in local gravity which can vary from place to place on our planet's surface and were measured by sensitive instruments aboard GOCE.

The quake in Japan had clearly ruptured the gravity field and left evidence of its effects, those instruments revealed.

Local gravity can vary because material inside Earth is inhomogeneous and unevenly distributed, and significant changes in its distribution -- as occurred in the 2011 temblor -- can cause additional variations in it, the researchers said.

The GOCE satellite mapped Earth's gravity with unrivaled precision for over four years, but nobody really expected the data to show changes over time, they said -- until the Japanese earthquake proved them wrong.

The satellite data proved large earthquakes not only deform Earth's crust, but can also cause tiny but permanent changes in local gravity, knowledge that can improve understanding of earthquakes and their consequences, the researchers said.

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