'Spacequakes" Disrupting Earth's Magnetic Field

Spacequakes contribute to auroras in the night sky.

Called “spacequakes,” bursts of plasma flying off of the sun are disrupting Earth’s magnetic field with the strength of a sizeable earthquake, according to new scientific evidence.

“The total energy in a spacequake can rival that of a magnitude 5 or 6 earthquake,” Evgeny Panov of the Space Research Institute in Austria tells the Christian Science Monitor. He is first author of a paper reporting the results of a study on spacequakes in the April 2010 issue of Geophysical Research Letters.

NASA’s THEMIS space probes discovered the precursors of spacequakes in 2007. According to the Monitor: 

The action begins in Earth's magnetic tail, which is stretched out like a windsock by the million-miles-per-hour solar wind. Sometimes the tail can become so stretched and tension-filled, it snaps back like an over-torqued rubber band. Solar wind plasma trapped in the tail hurtles toward Earth. 

On more than one occasion, the five THEMIS spacecraft were in the line of fire when these “plasma jets” swept by. Clearly, the jets were going to hit Earth. But what would happen then? The fleet moved closer to the planet to find out. 

“Now we know," said THEMIS project scientist David Sibeck of NASA's Goddard Space Flight Center. “Plasma jets trigger spacequakes.”

Research shows that the plasma jets crash into Earth’s geomagnetic field some 18,600 miles above the equator. The impact sets off a rebounding process, in which the incoming plasma actually bounces up and down on the reverberating magnetic field. The first bounce is a big one, followed by bounces of decreasing amplitude as energy is dissipated in the carpet.

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