Quakes's Jolting Effect Leaves The Earth Ringing
By Andy Geller
This changed the Earth's mass.
As the mass returns to normal, it moves back and forth, much like a church bell when struck by a tong, said Stony Brook geophysicist Teng-fong Wong.
The phenomenon was observed after the 9.5-magnitude quake in Chile in 1960 and the 9.2 magnitude temblor in Alaska in 1964.
After both quakes, the ringing lasted for three days, getting smaller every day.
The ringing now should last about that long and there's no need to worry.
Scientists say it's harmless. "Everything will calm down. We don't have any reason to be scared," said Constantin Cranganu, a geophysics prof at Brooklyn College.
Of far greater concern is the strong possibility of aftershocks as the geological plates adjust.
These could measure 6.0 to 7.0 on the Richter scale, the size of many earthquakes, and so could cause additional damage, said Lamont-Doherty seismologist Art Lerner-Lam.
He said, however, that it's unlikely the tremors will trigger the tsunamis, or killer waves, that caused most of the death and destruction in Sunday's quake.
Lerner-Lam said the aftershocks could last for months, although their size and frequency will die down.
The quake caused a shift in the Earth's rotation, as the change in the planet's mass altered the effect of the pull of gravity on the Earth.
But not to worry. The same thing happens in the summer and winter. It's harmless and it shouldn't last long.
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