Japan Quake Tremors Felt in Space!

by Agencies , IndiaTimes | March 13, 2013, 6:00 am IST

japan earthquake

The massive earthquake that hit Japan on March 11, 2011 was also felt in space by ESA's hyper-sensitive GOCE satellite.

The massive earthquake sent ripples of sound - called infrasound - upwards through the atmosphere.

These sound waves caused changes in air density that were detected by ESA's GOCE gravity satellite as it crossed the wavefront.


The size of these waves changes from centimetres at the surface to kilometres in the thin atmosphere at altitudes of 200-300 km.

Only low-frequency sound - infrasound - reaches these heights. It causes vertical movements that expand and contract the atmosphere by accelerating air particles.

Since it was launched in 2009, GOCE has been mapping Earth's gravity with unrivalled precision, orbiting at the lowest altitude of any observation satellite.



While the measurements ensure that GOCE remains ultra-stable in its low orbit to collect ultra-precise measurements of Earth's gravity, atmospheric density and vertical winds along its path can be inferred from the thruster and accelerometer data.

Exploiting GOCE data to the maximum, scientists from the Research Institute in Astrophysics and Planetology in France, the French space agency CNES, the Institute of Earth Physics of Paris and Delft University of Technology in the Netherlands, supported by ESA's Earth Observation Support to Science Element, have been studying past measurements.


Raphael Garcia from the Research Institute in Astrophysics and Planetology said, "Seismologists are particularly excited by this discovery because they were virtually the only Earth scientists without a space-based instrument directly comparable to those deployed on the ground.

"With this new tool they can start to look up into space to understand what is going on under their feet," he said.