This article is from the source 'bbc' and was first published or seen on . It will not be checked again for changes.
You can find the current article at its original source at http://news.bbc.co.uk/go/rss/-/1/hi/world/americas/8547955.stm
The article has changed 2 times. There is an RSS feed of changes available.
Previous version
1
Next version
Version 0 | Version 1 |
---|---|
How Chile's quake could have shortened a day | How Chile's quake could have shortened a day |
(about 21 hours later) | |
Nasa scientists believe Chile's devastating earthquake may have speeded up the Earth's rotation and shortened the length of a day. | Nasa scientists believe Chile's devastating earthquake may have speeded up the Earth's rotation and shortened the length of a day. |
Researcher Richard Gross and his colleagues at Nasa's Jet Propulsion Laboratory in California calculated that Saturday's 8.8-magnitude quake could have cut 1.26 microseconds off the length of a day. | Researcher Richard Gross and his colleagues at Nasa's Jet Propulsion Laboratory in California calculated that Saturday's 8.8-magnitude quake could have cut 1.26 microseconds off the length of a day. |
Not that anyone would notice however - as that's one-millionth of a second. | Not that anyone would notice however - as that's one-millionth of a second. |
But why does movement in the Earth's crust give the planet an apparent turbo boost? | But why does movement in the Earth's crust give the planet an apparent turbo boost? |
How an earthquake could shorten a day{current} of {total}NEXTBACK | How an earthquake could shorten a day{current} of {total}NEXTBACK |
Brian Baptie, of the British Geological Survey, explains how the Earth's lack of rigidity is what allows changes to the planet's rotation - and the length of a day. | Brian Baptie, of the British Geological Survey, explains how the Earth's lack of rigidity is what allows changes to the planet's rotation - and the length of a day. |
"The earth is not rigid and movements of its constituent parts, including the atmosphere and oceans, occur. These effects introduce a wobble - a movement of the Earth's axis - which is small but detectable," he says. | "The earth is not rigid and movements of its constituent parts, including the atmosphere and oceans, occur. These effects introduce a wobble - a movement of the Earth's axis - which is small but detectable," he says. |
"A small wobble can be caused as a result of great earthquakes like the recent event in Chile and Indonesia on 26 December 2004, due to the movement of mass close to the earth's surface, but it will only be marginally detectable by the most sensitive instruments and is not a cause for concern." | "A small wobble can be caused as a result of great earthquakes like the recent event in Chile and Indonesia on 26 December 2004, due to the movement of mass close to the earth's surface, but it will only be marginally detectable by the most sensitive instruments and is not a cause for concern." |
Using the same mathematical model as it used for Chile, the Nasa team had estimated the 9.1 Sumatran earthquake in 2004 would have shortened a day by 6.8 microseconds. | Using the same mathematical model as it used for Chile, the Nasa team had estimated the 9.1 Sumatran earthquake in 2004 would have shortened a day by 6.8 microseconds. |
But, as Nasa and other scientists also point out, the Earth's rotation rate changes all the time as a result of variations in winds and ocean currents, and doesn't have much practical consequence for people because of the tiny amount of time involved. |
Previous version
1
Next version