# Gravity anomaly of a dipping prism

1. Mar 8, 2012

### whatsoever

I am trying to write a matlab script which calculates the gravity anomaly of a dipping prism, using the equations of Hjelt, published in Geoexploration in 1974, issue 1 volume 12.
Δg=G.Δρ.T0
where
http://img580.imageshack.us/img580/6528/41828644.png [Broken]
and
http://img31.imageshack.us/img31/4226/phiih.png [Broken]
at the end of the page there are two notes, the second one says:
"Note 2: The sign of each $\phi$ is positive, whenever there is an even number of 2s in the indices
of u, v and w. (u1, - v1 - w1, u1 - v2 - w2, etc.)"

I just can't get my head around what exactly this means and how to apply it.I have expanded the equations for each $\phi$, using the limits for u, v and w, but they are very long, so will post them only if needed.

Last edited by a moderator: May 5, 2017
2. Mar 10, 2012

### NullSpaceMan

I had a quick read of the paper. Granted, the notation that the author uses is not clear and rather cumbersome.

I am not sure whether this helps, but if I were you, I would derive the gravity effect formula for a simple case (i.e. rectangular prism, semi-infinite slab, etc) and see how the results work out.

I do not have it at hand right now, but Telford et al., 1990 (Applied Geophysics) has a decent section on gravity methods. I would also take a look at Telford as I recall the notation is clearer.

cheers.

Last edited: Mar 10, 2012
3. Mar 11, 2012

### whatsoever

I think Telford gives the equations only for 2D anomalies