Re: Detemining gradient at individual points

Hi,

I am grateful for your concerned reply Dr. Wessel. I actaully have the slab grid file and latitude and longitude of few points. I need to find the dip of the slab at exactly those points. I am using the grdgradient command in the following manner:


grdgradient slabsurf2.grd -Dn -Sgradient.grd -V


I don't know where in the above command line, I need to put the latitude and longitudes of those points, where I actually want to calculate the dip of the slab. Should I make a separate text file having coordinates of those points and use that text file in the above command somewhere. I would be extremely grateful for any suggestions.


Thanks

Abhash kumar

University of North Carolina at Chapel Hill

________________________________
From: World-Wide GMT Usage and Help Mailing List <[email protected]> on behalf of Paul Wessel <[email protected]>
Sent: Wednesday, February 12, 2014 8:55 PM
To: [email protected]
Subject: Re: [GMT-HELP] Detemining gradient at individual points

Hi Abhash-

That is a good question.  However, grdgradient with -D and -S can also return the direction of the gradient or the strike (-Dn), as well as the absolute value of the gradient.  If your units are correct (all meters or geographic with -fg (or -M in GMT4)) then take atan of the gradient and that should give you dip, no?

-p

On Feb 12, 2014, at 3:37 PM, Mr Abhash Kumar <[email protected]<mailto:[email protected]>> wrote:

Hi,
I have a 2-D grid file for the subducting slab surface. I need to find dip of the slab at a particular latitude and longitude. I looked at the man page of grdgradient and it can only calculate the gradient along a particular azimuth. I would be extremely grateful for any suggestions in this regards.

Thanks
Abhash kumar
PHD candidate
University of North Carolina at Chapel Hill
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