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Sunday, June 30, 2013

Russian meteor shock wave traveled the globe twice

The resulting shock wave had a significant impact on the city of Chelyabinsk.

Do you remember the meteor that blazed a trail across the Russian sky on February 15, 2013? The resulting shock wave had a major impact on the city of Chelyabinsk, leading to property damage and causing more than 1,500 injuries to the city’s residents. Now, scientists, supervised by Alexis Le Pichon of the French Atomic Energy Commission, believe that the shock wave was so strong that it traveled the globe twice.

“For the first time since the establishment of the IMS infrasound network, multiple arrivals involving waves that traveled twice round the globe have been clearly identified,” the scientists write in a paper recently published in the journal Geophysical Research Letters.
The Global Seismic Network and EarthScope Transportable Array also measured the shock wave as it traveled across the United States.

“These recordings of seismic waves through the Earth, and sound waves through the atmosphere, are good examples of how these facilities can help global organizations better monitor earthquakes, clandestine nuclear tests and other threats,” said Greg Anderson, program director in NSF’s Division of Earth Sciences, in a news release.

Le Pichon and his team obtained data from 20 International Monitoring System stations worldwide to get an accurate idea of how much explosive energy was released when the meteor slammed into Chelyabinsk.

“A preliminary estimate of the explosive energy using empirical period-yield scaling relations gives a value of 460 kilotons of TNT equivalent,” the scientists add. Discovery News notes that this is the equivalent of 30 Hiroshima-sized atomic bombs.

According to measurements obtained by Peter Brown at the University of Western Ontario, the meteor is believed to have been approximately 17 meters across with a mass of 7,000-10,000 tons when it entered the atmosphere.

This energy estimate makes the Chelyabinsk event by far the largest space explosion since the 1908 Tunguska event, which destroyed millions of trees over an area of 830 square miles.

According to the BBC, the Tunguska event is believed to have had an energy equivalent to three to five megatons of TNT.

After the Chelyabinsk event, there was concern that this sort of undetected meteor event could happen again, and in a more populated region of the world. Four days after the event the European Space Agency pointed out that events of this significance are estimated to take place once every ten to 100 years.

Government are taking the threat of near-Earth objects extremely seriously. In fact, NASA has its own near-Earth object detection and tracking effort called the Near Earth Object Program.

In collaboration with the Jet Propulsion Laboratory, the Near Earth Object program recently announced the discovery of its 10,000 near-Earth object in space.
When and where will the next meteor impact take place? Share your thoughts in the comments section.

Source: http://thespacereporter.com

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