Chile Earthquake: Earth axis shifts shortening our days

The 8.8 magnitude earthquake in Chile last week was so powerful that it may have shifted the Earth’s axis by about three inches shortening our days by 1.26 millionth of a second. The shortening of our days by that much amount won’t have any directly perceivable changes in the environment such as season or temperature changes. You can’t show this to be the reason for coming late to the office either. Here are some details of what happened.

The Facts

The 8.8 magnitude earthquake is not a minor trembler by any means. It is a massive earthquake and NASA scientists speculates that Earth’s axis have altered permanently as some inevitable redistribution of mass has occurred. This would make our days shorter by approximately 1.26 microseconds. For your information, a microsecond is one-millionth of a second, if you didn’t already knew it. NASA also tells that the 3 inches (8 cm or 27 milliarcseconds) shift was due to the location of the quake. The fault sliced through the earth at a steeper angle and it was more effective in moving the earth’s mass vertically. This caused more effective shifting of Earth’s figure axis. The figure axis is the axis around which the Earth’s mass is balanced. It is offset from the Earth’s north-south axis by about 33 feet (10 meters).

Some Basics

Any mass movement on a rotating body may cause change in rotational speeds of the body. A popular analogy of the situation is that of a figure skater. To spin faster, she moves her arms closer to her body. Scientifically speaking, if any mass comes closer to its axis, the rotational speed increases. The same has happened to earth. The mass shift has caused the earth to rotate a bit faster thereby shortening our days. In fact, any mass movement on earth could cause shortening of our days. But in that case, to do even the slightest perceivable change, the effort required would be huge. If three Gorges reservoir in China were filled by 10 trillion gallons of water, the mass movement would change the rotational speed of the earth so that our days will be elongated by 0.06 microseconds.

Were there any other shifts in recent past?

Yes, back in 2004 there was a 9.1 magnitude earthquake that created a gigantic tsunami in the Indian Ocean. That also caused shortening of our days. It cut short 6.8 microseconds from everyday of our lives.

More information

The Chile Earthquake killed more than 700 people. The devastation and loss of other properties were also nothing less. But some parts of Chile have escaped from the damage. The European Southern Observatory managing team has confirmed that several major telescopes in Chile’s Atacama Desert were not damaged. A salt measuring satellite instrument of NASA was also left unharmed. The instrument would be installed on an Argentinean Satellite. The integration center is about 365 miles or 580 km away from the actual epicenter of the quake. The Aquarius instrument would provide monthly global maps of ocean’s salt concentration to track its current circulation and the role in climate change.