gravity field separation lecture, undergraduate geophysics course.

1. Gravity Field Separation
Gravity Field=
Regional + Residual
Regional Field comes from deep seated
structures like Moho
Residual field comes from shallow (near
surface) structures

2. Example
Observed gravity (Bouguer) map

3. Using graphical separation method

4. Regional field

5. Residual field

6.  Regional fields are generally
smoother than residual>
 Residual anomalies are usually
higher in amplitude

7. Separation Methods
 Graphical method:
Depends on removing the trend
( regional) from Bouguer anomalies.
 Griffin Method
Applying averaging scheme to
gravity maps through averaging the gravity
values around a point then subtracting from
the gravity value at the point to get the
residuals.

8. Another example