Tectonics through geodesy (GPS)

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Tectonics through geodesy (GPS)
Wednesday 1600-1730
Rocco Malservisi e-mail malservisi_at_geophysik.
uni-muenchen.de phone [phone]
Class Web page www.geophysik.lmu.de/malservisi/T
ectGPS.html
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What is GEODESY?
From Greek DIVIDING THE EARTH
Geodesy is the branch of applied mathematics
concerned with the determination of the size and
shape of the Earth, with the exact positions of
points on its surface, and with the description
of variations of its gravity field.
International Association of Geodesy definition
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What does this means?
How big is the Earth?
Where am I?
How far am I from a place?
Which is the shape of the planet?
In which direction should I go?
How tall is a mountain?
Where my property ends?
How big is my property?
Geodesy is answering these questions
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Who care about the shape of the Earth?
If we want to have a mathematical representation
of a point (points coordinate) we need to have a
reference surface we can refer to. Knowing the
shape of the Earth we can define this
surface. The gravity field gives the best
representation of the shape of the Earth.
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The shape of the Earth?
The Earth is almost a sphere with a
circumference 40000 km long The meter was
defined using this length.
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The shape of the Earth?
Eratosthenes (215 BC)
S4400 stadia 787km Q7.2 C39376km
R 6267 km
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The shape of the Earth?
XVII XVIII Century Discussion of Oblate-Prolate
spheroid
Cassini meridian south of France shorter than in
Paris PROLATE
British Pendulum slower at equator and Newton
equations OBLATE
XVIII Century (1730) Expedition of France
Academy Peru measurement 6376.45 km (Equatorial
Radius) Lapland measurement 6355.88 km (Polar
Radius) OBLATE!! Difference 1350m in 111km!!!
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The shape of the Earth?
The Earth is almost a sphere with a
circumference 40000 km long The meter was
defined using this length.
Better approximate by an oblate ellipsoid
Today accepted Value Equatorial Radius 6378
km Polar Radius 6357 km Sphere of Equal
Volume Radius 6371 km Flattening 1/298.25722356
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The shape of the Earth?
The real shape of the planet is approximated by
the Geoid THE EQUIPOTENTIAL SURFACE AT THE MEAN
SEA LEVEL
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We can divide geodesy
According to what we observe
According to method
OR
Global Geodesy Determination of shape of the
Earth, global references. Geodetic
Survey Determination of positions, and references
over a region for which the Earths curva- ture
can have influences. Plane Survey Determination
of positions and references on a local level.
Space Geodesy use of extra-terrestrial object as
observable. Terrestrial Geodesy Use of
terrestrial tools And observable
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TRADITIONAL SURVEY
Horizontal positioning
Vertical positioning
TRIANGULATION
GEODETIC LEVELING
TRILATERATION
TRIGONOMETRIC HEIGHTING
TRAVERSING
BAROMETRIC LEVELING
ASTRONOMICAL POSITIONING
TILTING
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TRADITIONAL SURVEY
Horizontal positioning
TRIANGULATION
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TRADITIONAL SURVEY
Horizontal positioning
TRILATERATION
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TRADITIONAL SURVEY
Horizontal positioning
TRAVERSE
EDM
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TRADITIONAL SURVEY
Vertical positioning
GEODETIC LEVELING
TRIGONOMETRIC HEIGHTING
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SPACE SURVEY
VLBI Very Long Baseline Interferometry
SLR Satellite Laser Ranging
GPS Global Positioning System Glonass
Galileo
DORIS
InSAR Interferometric Synthetic Aperture Radar
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Very Long Baseline Interferometry

• VLBI is a geometric technique
• It measures the time difference between the
  arrival at two Earth-based antennas of a radio
  wavefront emitted by a distant quasar.
• Using large numbers of time difference
  measurements from many quasars observed with a
  global network of antennas, VLBI determines the
  inertial reference frame defined by the quasars
  and simultaneously the precise positions of the
  antennas.

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SLR Satellite Laser Ranging
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The Global Positioning System

• The Global Positioning System (GPS) is a
  satellite-based navigation system.
• GPS was originally intended for military
  applications, but in the 1980s, the government
  made the system available for civilian use.
• GPS works in any weather conditions, anywhere in
  the world, 24 hours a day. There are no
  subscription fees or setup charges to use GPS
• Some civilian uses
• Navigation on land, sea, air
• and space
• Geophysics research
• Guidance systems
• Geodetic network densification
• Hydrographic surveys

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Glonass GLObal NAvigation Satellite System
Glonass is a Soviet space-based navigation system
comparable to the American GPS system. The
operational system contains 21 satellites in 3
orbital planes, with 3 on-orbit spares.
Glonass provides 100 meters accuracy with its
C/A (deliberately degraded) signals and 10-20
meter accuracy with its P (military) signals.
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DORIS
Doppler Orbitography and Radio positioning
Integrated by Satellite Precise orbit
determination and location system using Doppler
shift measurement techniques. A global network
of 52 Doris orbitography beacons has been
deployed. Doris was developed by Cnes, the French
space agency, and is operated by CLS.
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InSAR

• Two or more data acquisition of the same area
  from nearby location (lt 1000 m)
• Enables detection of surface changes within cm
  level accuracy

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