The Japan Earthquake Weakened Japan's Gravity

The Japan earthquake in March was big. Obviously. But recent satellite analysis by researchers reveal it was so big that it actually affected the gravitational field surrounding Japan.

According to the Christian Science Monitor, the uneven mass distribution on Earth means Gravity has different magnitudes in different places. The earthquake was strong enough to produce a measurable difference because it thinned out the crust around Japan.

The researchers found the Tohoku-Oki quake reduced the gravity field there by an average of two- millionths of a gal by slightly thinning the Earth's crust. In comparison, the strength of the gravitational pull at the Earth's surface is, on average, 980 gals. (The gal, short for Galileo, is a unit of acceleration; one gal is defined as one centimeter per second squared.)

That may be a small amount, but still, affecting Gravity at all is insane. [CS Monitor] Note: Headline originally read "Japan Earthquake Weakened Earth's Gravity" which, as Bob points out, is a little misleading. The article itself explains the Japan localisation, and the headline has been updated to reflect this. Meanwhile Bob (and all readers) -- we're happy for you to point out stuff like that. Just please don't be a dick about it.