posted 03-13-2011 04:02 PM               

Aerial photos taken over Japan have revealed the scale of devastation across dozens of suburbs and tens of thousands of homes and businesses.

Hover over each satellite photo to view the devastation caused by the earthquake and tsunami.

posted 03-13-2011 08:39 PM               

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Originally posted by GoesTo11:
Japan moved 8 feet to the east, and the Earth moved 2 cm off its axis.

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• Is Japan now 8 feet farther away from Korea?
  
• Is every GPS device in Japan now off by 8 feet?

posted 03-14-2011 10:05 AM               

Newton taught us every action must have an equal and opposite reaction. So to move the axis, what was the reaction? Space ships (ISS) can rotate about their axis with gyros so I can understand the Earth's axis could technically be moved or tilted but wouldn't that be an angular measurement, not a liner one?

I can only find a legit source that quotes "one GPS station moved 8 inches." Heck, anyone can take a bulldozer and move a GPS station 8 inches. That doesn't meant the Earth moved, or its axis moved, or the sky is falling...

As scientists, we need to be careful what we read from over anxious journalists. Remember the old saying "if its on TV it must be true." The Internet is obviously the new TV.

I hope real scientists are using real spacecraft and real math equations to see how much the earth really tilted its axis or if it was really displaced.

posted 03-14-2011 11:31 AM               

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Originally posted by mercsim:
Newton taught us every action must have an equal and opposite reaction. So to move the axis, what was the reaction?

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posted 03-15-2011 07:12 AM               

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Originally posted by dom:
I know this is technically a space forum but can we show a little more respect towards the tens of thousands of dead.

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posted 03-15-2011 10:36 AM               

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Originally posted by mercsim:
As scientists, we should be asking "where's the data?"

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Using a United States Geological Survey estimate for how the fault responsible for the earthquake slipped, research scientist Richard Gross of NASA's Jet Propulsion Laboratory, Pasadena, Calif., applied a complex model to perform a preliminary theoretical calculation of how the Japan earthquake -- the fifth largest since 1900 -- affected Earth's rotation. His calculations indicate that by changing the distribution of Earth's mass, the Japanese earthquake should have caused Earth to rotate a bit faster, shortening the length of the day by about 1.8 microseconds (a microsecond is one millionth of a second).

The calculations also show the Japan quake should have shifted the position of Earth's figure axis (the axis about which Earth's mass is balanced) by about 17 centimeters (6.5 inches), towards 133 degrees east longitude. Earth's figure axis should not be confused with its north-south axis; they are offset by about 10 meters (about 33 feet). This shift in Earth's figure axis will cause Earth to wobble a bit differently as it rotates, but it will not cause a shift of Earth's axis in space -- only external forces such as the gravitational attraction of the sun, moon and planets can do that.

Both calculations will likely change as data on the quake are further refined...

Gross said that while we can measure the effects of the atmosphere and ocean on Earth's rotation, the effects of earthquakes, at least up until now, have been too small to measure. The computed change in the length of day caused by earthquakes is much smaller than the accuracy with which scientists can currently measure changes in the length of the day. However, since the position of the figure axis can be measured to an accuracy of about 5 centimeters (2 inches), the estimated 17-centimeter shift in the figure axis from the Japan quake may actually be large enough to observe if scientists can adequately remove the larger effects of the atmosphere and ocean from the Earth rotation measurements. He and other scientists will be investigating this as more data become available.

posted 03-15-2011 09:45 PM               

Moving an island (or tectonic plate) 8 inches could affect the axis as I pointed out earlier using the ISS as an example.

Gross says "Over the course of a year, the length of the day increases and decreases by about a millisecond, or about 550 times larger than the change caused by the Japanese earthquake" so it appears the news is making something big without giving all the details. Typical news...

posted 03-15-2011 10:42 PM               

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Originally posted by mercsim:
Basic physics says the re-distribution of mass needs to be towards the center of rotation and I haven't seen this mentioned anywhere.

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posted 03-30-2011 08:01 AM               

Earth movements from Japan earthquake seen from space

Satellite images have been essential for helping relief efforts in Japan following the massive quake that struck on 11 March. Now scientists are using ESA's space radars to improve our understanding of tectonic events.

Scientists are calling on data from the advanced radar on ESA's Envisat satellite to map surface deformations caused by the magnitude 9 earthquake.

Studying data acquired on 19 February and 21 March, scientists from NASA's Jet Propulsion Laboratory have detected a ground shift of about 2.5 m eastwards and a downward motion of Honshu Island's east coast.

Scientists from Italy's Istituto Nazionale di Geofisica e Vulcanologia have used the same Envisat data to show a large portion of the surface displacement, with a maximum shift of 2.5 m.

These first results, covering an 800 km-long strip over Sendai and Tokyo, show movement far away from the epicentre (denoted by the red star in the top image) in the Pacific Ocean.

The complex technique being used by the scientists is known as 'InSAR' - synthetic aperture radar interferometry. It combines before and after radar images of the same ground location from the same position in space in such a way as to detect ground motion down to a few millimetres.

These analyses could only be made now because Envisat's orbit repeats every 30 days. After capturing the area on 19 February -before the earthquake - Envisat's repeat scan from the same position in space came on 21 March. Envisat is still making repeat visits to cover the full area.

Another veteran ESA satellite is also contributing to the Japan radar coverage. After 16 productive years, ERS-2 will end its mission this year, but its repeat cycle was fortuitously changed earlier this month from 35 days to 3 days to collect innovative radar information.

Its three-day repetition is providing partial coverage over Japan, north of Sendai. Collection of ERS-2 radar data over this area began after the main earthquake with the aim of mapping the aftershocks. Scientists are now working on these data.

This disaster marks the first time that multiple space agencies - ESA, the German Aerospace Center and the Japan Aerospace Exploration Agency - are openly providing SAR data for understanding tectonic processes under the GeoHazard Supersites initiative, coordinated by the Group on Earth Observations.

The initiative is stimulating international efforts and fostering collaboration between space agencies, in-situ data providers and users to further our understanding of geological risks.

The initiative provides scientists with access to in-situ and spaceborne data, including 20 years of satellite radar observations.

This joint collaboration, incorporating all available space and ground data, is an efficient way to make significant progress in assessing the area's future vulnerability while reconstruction is under way.