Plate Tectonics
Earth is divided into 15 plates,
about 100 km thick,
floating on the Earth's surface on molten magma.
Plate Tectonics, Geodesy, and VLBI
1
Do the continents fit like a puzzle?
© F-Secure Corporation
The West African coastline and the East coast
of South America
Northeast Africa and Arabian peninsula
Plate Tectonics, Geodesy, and VLBI
2
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)
Plate Tectonics, Geodesy, and VLBI
3
How do scientists measure
continental drift?
Very
Long
Baseline
Interferometry
Radio telescopes at
different sites
investigate the motion
of the Earth’s tectonic
plates. See more
Plate Tectonics, Geodesy, and VLBI
4
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.
Plate Tectonics, Geodesy, and VLBI
5
Radio
Telescope
Plate Tectonics, Geodesy, and VLBI
6
Continental Drift between
North America and Europe
Picture by Axel Nothnagel
Westford, Massachusetts
Wettzell, Germany
Plate Tectonics, Geodesy, and VLBI
7
Simple but Precise
 What are the limits
and uncertainty of
VLBI measurements?
Westford,, MA USA
 How may they be
resolved?
Wettzell, Germany
Plate Tectonics, Geodesy, and VLBI
8
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?
Plate Tectonics, Geodesy, and VLBI
9
Uncertainty in the VLBI Measurements (Westford to Wettzell)
0.045
Uncertainty in Measurement (m)
0.040
0.035
0.030
0.025
0.020
0.015
0.010
0.005
0.000
1983
1986
1989
1992
1995
1998
2001
2004
2007
Epoch
Plate Tectonics, Geodesy, and VLBI
10
Continental
Drift
between
0.75
North America and Europe
0.65
C
Change in Distance (m)
Change in Distance (D) from Westford to Wettzell vs. Epoch
0.55
C
0.45
D Distance = 0.01679 (Epoch) - 32.98
R2 = 0.989
0.35
Base = 5995.325 km
0.25
Westford, Massachusetts
1983
1986
1989
1992
1995
Epoch
Wettzell, Germany
1998
2001
2004
Plate Tectonics, Geodesy, and VLBI
2007
11
Seasonality Correlation
Variation from Regression
0.02
0.01
0
-0.01
-0.02
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
Year
Plate Tectonics, Geodesy, and VLBI
12