Before the ’04 Tsunami, an Earthquake So Violent It Even Shook Gravity

In summary, the Gravity Recovery and Climate Experiment (Grace) satellites recorded a sudden drop in gravity near the epicenter of an earthquake in Sumatra. This is possible due to the displacement of a large mass, causing a temporary shift in the Earth's gravitational field. Aerial measurements of gravity can be useful for various purposes, including identifying ore deposits. These measurements also reveal inhomogeneities in mass distribution on the planet. However, it is important to note that a drop in gravity is not a change in physics, but rather a result of changes in topography.
  • #1
scott1
350
1
Two identical satellites, collectively known as the Gravity Recovery and Climate Experiment, or Grace, travel one behind the other in a polar orbit separated by about 130 miles.
Grace recorded a sudden drop in gravity near the quake’s epicenter off Sumatra.
http://www.nytimes.com/2006/08/08/s...1980f607&ei=5090&partner=rssuserland&emc=rss"
How is it possible to have a drop in gravity when a Earth quake happens?
 
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  • #2
Not my field, but I can't see it happening on the whole. If the quake was big enough, maybe it caused a temporary shift in the centre of gravity. If the satellite was aimed at a small, specific area, maybe there was a local drop.
 
  • #3
Aerial measurements of gravity are useful for various purposes, eg. identifying economically feasible ore deposits. Try googling "Gravity Recovery and Climate Experiment"?
 
  • #4
A large mass was suddenly displaced, thus the Earth's gravitational field was slightly altered, very suddenly. A planet is not a uniform sphere; there are inhomogenities in mass distribution, which can be mapped by measuring the gravitational field. Look at the picture - the scale is in parts per 10^-5, these are very tiny differnces.

Note carefully - "drop in gravity" is not a change of physics, it's simply the result of a change of topography.
 

1. What caused the earthquake that led to the 2004 tsunami?

The earthquake that triggered the 2004 tsunami was caused by the sudden movement of tectonic plates beneath the Indian Ocean. This type of earthquake is known as a subduction zone earthquake, where one tectonic plate is forced beneath another.

2. How strong was the earthquake?

The earthquake that occurred before the 2004 tsunami had a magnitude of 9.1-9.3 on the Richter scale, making it one of the strongest earthquakes ever recorded. It released the energy equivalent of 23,000 Hiroshima-type atomic bombs.

3. How did the earthquake affect gravity?

The 2004 earthquake was so powerful that it caused small fluctuations in the Earth's gravity. This is because the sudden movement of tectonic plates changes the distribution of mass within the Earth, altering its gravitational field.

4. Was the earthquake predicted?

No, the earthquake that preceded the 2004 tsunami was not predicted. While scientists had identified the potential for a major earthquake in the region, the specific timing and magnitude were not known.

5. Has there been an earthquake as powerful as the one before the 2004 tsunami since then?

No, the 2004 earthquake was one of the strongest ever recorded. While there have been other powerful earthquakes since then, none have reached the same magnitude as the one that caused the 2004 tsunami.

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