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Gravity Method
By
Dr. Amin E. Khalil
2
21
r
MM
GF
gMF
2
21
2
r
MM
GgM
2
r
M
Gg
R = radius of the earth
Earth is considered as
sphere and hence
radius is constant.
Earth is not sphere and hence radius
is not constant.
Hence correction must be applied
Because many factors affect the
value of g. As an example:
•Earth flattening.
•Surface relief.
• anomalous masses inside t...
What is geoid?
It is equipotential surface where the g
is always constant. The equipotential
surface is usually taken as t...
Reduction is carried out to correct for:
•Latitude
•Elevation
•Excess mass
•Terrain
•Drift
•Isostacy
•Earth’s rotation
The earth is flattened,
i.e the radius at the
equator is longer than
at the poles.
gn = 978031.85 (1.0 + 0.005278895 sin2(...
geoid
gb = gobs - gn + 0.3086h - 0.04193r h (mGal)
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Gravity method

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undergraduate gravity lecture

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Transcript of "Gravity method"

  1. 1. Gravity Method By Dr. Amin E. Khalil
  2. 2. 2 21 r MM GF
  3. 3. gMF 2 21 2 r MM GgM 2 r M Gg
  4. 4. R = radius of the earth Earth is considered as sphere and hence radius is constant.
  5. 5. Earth is not sphere and hence radius is not constant. Hence correction must be applied
  6. 6. Because many factors affect the value of g. As an example: •Earth flattening. •Surface relief. • anomalous masses inside the earth
  7. 7. What is geoid? It is equipotential surface where the g is always constant. The equipotential surface is usually taken as the sea level. However, due to some heterogeneity in the earth Geoid may differ slightly from Sea level.
  8. 8. Reduction is carried out to correct for: •Latitude •Elevation •Excess mass •Terrain •Drift •Isostacy •Earth’s rotation
  9. 9. The earth is flattened, i.e the radius at the equator is longer than at the poles. gn = 978031.85 (1.0 + 0.005278895 sin2(lat) + 0.000023462 sin4(lat)) (mGal)
  10. 10. geoid
  11. 11. gb = gobs - gn + 0.3086h - 0.04193r h (mGal)
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