Friday, April 1, 2011

The deformation of the Earth after an earthquake in Japan, seen from space

After the earthquake of nine degrees on the Richter scale that hit Japan in early March, a team of researchers from NASA's JPL laboratory measured the deformation of the Earth by comparing satellite images Envista, European Space Agency (ESA) . Compared the data of radar on board, collected on 19 February and 21 March, and have detected a shift in the field of 25 meters to the east and the collapse of the east coast of Honshu Island, the largest Japanese archipelago.

Scientists from the Italian National Institute of Geophysics and Volcanology have used the same Envisat observations to map the same displacement field, which confirmed the findings of NASA. The technique used is an interferometric synthetic aperture radar, known as InSAR and shows (see chart left) colored in red the areas that have suffered landslide.

These first results, covering a stretch of 800 km of Sendai and Tokyo, also show that the deformation of the terrain extends very far from the epicenter of the earthquake, marked with a red star in the picture, in the Pacific Ocean. To be compared interferometry radar images taken before and after the event from the same exact angle, allowing you to see geological changes to a few millimeters.

As the orbit of Envisat only repeats every thirty days [from the website of the Agency may be real-time where the satellite and what is attracting all the time] was not until last March 21 for the satellites were in the same position as when he took the image from 19 February. Space agencies share all their data for the first vezVarios satellite Earth observation, from different world's space agencies are playing a crucial role in coordinating rescue efforts after the earthquake and help scientists understand ESA tectonic phenomena better.

This natural disaster is the first time that several space agencies - the ESA, the German Aerospace Center (DLR) and the Japan Aerospace Exploration Agency (JAXA) - freely share their data obtained by SAR satellites to help better understand the tectonic processes of our planet, within the Geo-Hazard Supersite initiative, coordinated by the Group on Earth Observations (GEO).

This initiative provides access to in-situ observations and from space and has an archive of 20 years of radar observations.

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