California Surveyors Forums

A quake specialist on CNN last night said the revised magnitude is 9.1.

They think the entire main island shifted by 8 feet. Astonishing. And on top of that the earth's axis shifted by 4 inches. The tectonic plates slipped by 60 feet.

Looks like surveyor's have a lot of work to do once the cleanup is over.

http://www.cnn.com/2011/WORLD/asiapcf/0 ... tml?hpt=T1

So....

What happens to all those lovely coordinates now?

Just sayin'.


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Change your error ellipse to +/-4in. ;)

Might be interesting to GPS something mon that you GPS'd last thur.

Ian,

That's why coords are right down at the bottom of the evidence hierarchy along with area in most jurisdictions. but I heard a rumor that in West TX there is one surveyor who is already busy moving monuments to match the new location of the coords that are listed in the descriptions he writes.

Japan has a pretty advanced Geodetic real time network. It should not take a big effort to readjust the network of CGPS stations. The problem is that things are still moving over there and are bound to keep moving for months.

Revised Numbers: the island shifted by over 17 feet!

"Meanwhile, the March 11 tremors shifted the Oshika Peninsula near the epicenter by just over 17 feet and dropped it by just over 4 feet, the Geospatial Information Authority in Tsukuba, Japan, reported Saturday.

Those two land mass movements are records for Japan, according to government figures.

The global positioning system data from the Tsukuba University-based authority revealed the peninsula on the Pacific coast moved in an east-southeasterly direction toward the epicenter. The quake also moved land masses in many areas ranging from the northeastern region of Tohoku to the Kanto region including Tokyo, the authority said."

Full article: http://www.cnn.com/2011/WORLD/asiapcf/0 ... tml?hpt=T2

So much for setting lot corners from record coordinates.

Also from that article:

| Reports from the National Institute of Geophysics and Volcanology
| in Italy estimated the 8.9-magnitude quake shifted the planet on
| its axis by nearly 4 inches (10 centimeters).

What will that do to our GPS observations?

Its all relative

Indeed, the earth's axis wanders about quite a bit. The Chandler wobble has a magnitude of about 20 feet and a period of 433 days.

As RAM said, it's all relative.

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Did anyone on here happen to reGPS something they GPS's just before the quake?

So did the earth move? (pun intende) or just the plates that shifted? If just the plates, then there should not have been a change of the orienation of the earth and the sat's system. Did the sphere it's self re-orienate or just the objects on the surface of the sphere?

For some of us that is enghough deep thought for the week.

This is another one of those stories that sounds really important and impressive until you start to think about it.

What moved 10 centimeters?

How do you know it moved 10 centimeters?

What was the movement relative to?

What was the method of determining this movement?

What is the metadata for this measurement?

Most people don’t have enough science education to understand what any of this means. They’ll just say “Gee whiz!”, pop open another cold one and look for something else on TV.


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That damn Chandler...

it wobble from that beer or the quake?

"For some of us that is enghough deep thought for the week."

At least that long LOL