As you may already know, the 9.0 Magnitude earthquake on March 11, 2011 off the coast of Sendai-shi (Sendai City), Miyagi-ken (Miyagi Prefecture) shifted enough mass to make the Earth actually spin a bit faster--0.0000000003 of a second, making our year that much shorter. Essentially, it means a day is now 1.8 microseconds shorter. A microsecond is one-millionth of a second--keep in mind that it takes 350,000 microseconds to blink.
As previously described in a blog post here, the spinning is similar to what an ice figure skater does: As one moves the arms closer to the body, it moves the mas closer to the axis about which one rotates... you get faster as you bring the arms in closer.
It's been calculated that there was a 6.7-inch (17.0180 centimeter) shift in the axis of the Earth (the planet's balance point), which is about two-times as much as what was caused by the earthquake under the Indian Ocean in 2004 and in Chile in 2010.
The Earth has a NORTH-SOUTH axis that runs through the North and South poles. Our planet's mass balances around the figure axis which is about 33-feet (10.0584 meters) off the north-south axis.
It's not a very big shift, but it does affect the way we go about our space flights. Even a tiny change like this will affect the angle at which a spacecraft leaves Earth, which could affect the guidance across 10s of millions of miles (16 millions of kilometers)... which is important if you are trying to aim your spaceship to go to the moon... if you don't calculate correctly, you could miss it all together.
By the way... the 2004 earthquake actually slowed the Earth's spin (making the year a little bit longer), so the 2011 Sendai quake evened things up. Don't worry, you won't be late for work unless you want to be late for work.
As for Japan, the earthquake moved the big main island of Honshu a distance of 7.9-feet (2.40792 meters) east, making it closer to the U.S., and farther away from Europe and Asia.
The Pacific continental plate continues to slide under the North American plate, which causes tension. When the tension was released the land moved up and east, which is what actually caused the earthquake on March 11, 2011 and the shifting of the Japanese island of Honshu.
During the earthquake, the ocean floor moved up 130-feet (39.6240 meters) and slipped over an area 185-miles (297.729 kilometers) long (this was the shifting of the plate--plate tectonics) and 90-miles (144.841 kilometers) wide.
This movement caused a movement of water (about 16,000 feet (4,876.80 meters) of water) upwards, generating the tsunami--two actually, as one moved east towards the U.S. and the other west to Japan.
According to scientists, in the open waters of the Pacific Ocean, the tsunami was moving as fast as a commercial jet airliner, which is about 180 miles per hour (300 kilometers per hour). The tsunami wave actually slowed down, however, as it approached the coast of Japan, but the slope of the continental shelf raised the tsunami's maximum height to 121-feet (36.8808 meters) a little more than 80 miles (128.748 kilometers) away before hitting Japan.
Now go and amaze your friends with what you know.
From various files.
Andrew Joseph
