Plate TectonicsEarth is divided into 15 plates,

about 100 km thick,floating on the Earth's surface on molten

magma.

1Plate Tectonics, Geodesy, and VLBI

Do the continents fit like a puzzle?

The West African coastline and the East coastof South America

Northeast Africa and Arabian peninsula2

Plate Tectonics, Geodesy, and VLBI

© F-Secure Corporation

According to Tectonic Plate Theory;

• Once all continents

were compressed into one.Pangaea ("all lands")

• Over time they drifted apart into their current positions.

• Try fitting it yourself (Hit the green button)

3Plate Tectonics, Geodesy, and VLBI

How do scientists measure continental drift?

Radio telescopes at different sites investigate the motion of the Earth’s tectonic plates. See more

Very

Long

Baseline

Interferometry

4Plate Tectonics, Geodesy, and VLBI

How does VLBI work?

1. Two radio telescopes are looking at the same quasar.

2. Incoming radio wave signals are tagged with an atomic clock.

3. Signal arrival times at the two telescopes are compared.

4. The distance between them is calculated. 5Plate Tectonics, Geodesy, and VLBI

Radio Radio TelescopTelescop

ee

6Plate Tectonics, Geodesy, and VLBI

Continental Drift between North America and Europe

Westford, Massachusetts

Wettzell, Germany

7Plate Tectonics, Geodesy, and VLBI

Picture by Axel NothnagelPicture by Axel Nothnagel

Simple but Precise

Westford,, MA USAWettzell, Germany

What are the limits and uncertainty of VLBI measurements?

How may they be resolved?

8Plate Tectonics, Geodesy, and VLBI

Errors, errors, errors!!!• No matter how good

you are…there will always be errors.

• Every measurement has uncertainties and errors (unfortunately).

• The question is… How to deal with them?

9Plate Tectonics, Geodesy, and VLBI

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0.035

0.040

0.045

1983 1986 1989 1992 1995 1998 2001 2004 2007

Epoch

Un

cert

ain

ty i

n M

easu

rem

ent

(m)

Uncertainty in the VLBI Measurements (Westford to Wettzell)

10Plate Tectonics, Geodesy, and VLBI

Continental Drift between North America and Europe

Westford, Massachusetts

Wettzell, Germany

C

C

Change in Distance (D) from Westford to Wettzell vs. Epoch

D Distance = 0.01679 (Epoch) - 32.98

R2 = 0.989

0.25

0.35

0.45

0.55

0.65

0.75

1983 1986 1989 1992 1995 1998 2001 2004 2007

Epoch

Cha

nge

in D

ista

nce

(m)

Base = 5995.325 km

11Plate Tectonics, Geodesy, and VLBI

Seasonality Correlation

-0.02

-0.01

0

0.01

0.02

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007

Year

Varia

tion

from

Reg

ress

ion

12Plate Tectonics, Geodesy, and VLBI