New “Sunquake” Trigger Found: Huge Solar Belches Coronal mass ejections join solar flares as quake sources, study says.

Dave Mosher

for National Geographic News

Published April 5, 2012

Powerful earthquake-like events on the sun’s surface, called sunquakes, can be set off by huge belches of charged particles from the solar atmosphere, scientists say.

Researchers had previously linked sunquakes to solar flares, eruptions on the sun that can send powerful bursts of x-rays, ultraviolet light, and matter into space. (See video: “Solar Flares Cause ‘Sunquakes.’”)

On February 15, 2011, researchers spied two sunquakes and a solar flare that occurred around the same time—but the flare wasn’t hot enough to have spawned the seismic waves.

“The heat and radiation from solar flares is thought to drive a pressure wave to the surface, like thunder from a lightning bolt. But for this February 15th event, it wasn’t like that,” said Sergei Zharkov, a space scientist at University College London, who presented the new findings about sunquakes last month at the 2012 National Astronomy Meeting in Manchester, U.K.

Instead it appears the February sunquakes were linked to a coronal mass ejection, or CME, a huge cloud of charged solar particles that erupted from the sun’s upper atmosphere.

(Related: “‘Dark Fireworks’ Seen on Sun—Blast as Big as Ten Earths.”)

“This is the first time we’ve seen a sunquake associated with a coronal mass ejection,” Zharkov said. “It’s the first clear counterexample.”

Sunquakes Pack Powerful Punches

Solar researchers in 1972 predicted the existence of sunquakes, which look like the circular ripples on a pond’s surface after someone tosses in a stone.

It wasn’t until 1998, however, that a team of scientists announced the first observed sunquake, found in 1996 data from NASA’s Solar and Heliospheric Observatory. The 11.3-magnitude sunquake occurred following a solar flare, and it was 40,000 times more powerful than the 1906 San Francisco earthquake.

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