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Re: [Phys-l] Earth's axis shift--measured how?



Rick,

The referenced article quite clearly states such a change in rotation rate is likely immeasurable. I suspect what the Italians did was just calculate the change in the moment of inertia of the earth due to a postulated 50 ft? shift in the crust.

Someome of the gravitational satellites (now?) orbiting (GRACE, GOCE) are easily capable of detecing a shift in the gravitational field of the earth due to a large temblor so perhaps direct verification of the change in rate of rotation is not such an impossible thing. I am constantly astounded at how precise many of today's measurements can be.

Dan Beeker

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Message: 2
Date: Sat, 12 Mar 2011 13:05:17 -0500
From: "Richard Tarara"<rbtarara@sprynet.com>
Subject: [Phys-l] Earth's axis shift--measured how?
To: "Forum for Physics Educators"<phys-l@carnot.physics.buffalo.edu>
Message-ID:<4A720533DA264B12810678312EB57438@RickPC>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
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http://www.montrealgazette.com/news/world/Japan+quake+shifts+earth+axis/4428645/story.html

The question has been asked--measured where? Measured relative to what
exactly?

Anyone know for sure?

Rick


Richard W, Tarara
Professor of Physics
Saint Mary's College
Notre Dame, IN 46556

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