Massive Earthquake in Japan Heard from Space, New Study

According to a new study, the massive earthquake that struck Japan in 2011 with the magnitude of 9 was so large that it could be heard from space.

The European Space Agency's (ESA) Gravity Ocean Circulation Explorer (GOCE) satellite orbiting the Earth was able to sense the ultra-low frequency sound waves created by the massive earth quake that almost killed 19,000 people which also caused massive tsunami. The tsunami also hit the Fukushima Daiichi nuclear plant at that time which forced thousands of people to evacuate from their houses.

No spacecraft in orbit were able to record them until now. The satellite first recorded the Tohoku signal as it passed over the Pacific Ocean about 30 minutes after the quake. It was detected again 25 minutes later as it crossed Europe.

“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,” said Raphael Garcia, lead study author and physicist with the Research Institute in Astrophysics and Planetology in France.

Goce's main objective is to map subtle differences in the pull of gravity across the surface of the Earth caused by the uneven distribution of mass within the planet. Goce, however, is running low on fuel and is reaching the end of its mission.  

Dr. Rune Floberghagen from the European Space Agency (ESA) said in an interview with BBC News. “Goce’s accelerometers are about a hundred times more sensitive than any previous instrumentation and we detected the acoustic wave not once, but twice – passing through it over the Pacific and over Europe.”

“Ever since we’ve flown this type of instrument – accelerometers – in space, people have been looking for the acoustic beat from earthquakes, because that could be used to understand the way tremors propagate not only through the Earth but through the Earth environment.” Floberghagen added.

An official at the Japan Meteorological Agency, the major body that follows earthquakes in Japan, said it was rare to use a satellite for this type of analysis.

"Generally speaking, earthquakes are monitored using land-based seismographs. Satellites are not used to monitor earthquakes when they strike," he said.

The study was published in the journal Geophysical Research Letters.