From: Thorsten Becker <twb@usc.edu>
Date: April 3, 2009 10:07:49 AM PDT
To: "Sandwell, David" <dsandwell@ucsd.edu>, "kreemer@unr.edu"  
<kreemer@unr.edu>
Subject: Re: strain rate maps

Dave,

as said, great idea. As requested, here's a tar file with exx, exy, eyy
(eEE, eEN, eNN), in units of 10^{-15} 1/s, along with plots of the max
shear strain of the horizontal strain-rate tensor ((e_1-e_2)/2), and
the mean normal strain-rate ((e_1+e_2)/2) for reference. The strain
interpolation is from

Platt, J. P., Kaus, B. J. P. and Becker, T. W.: The San Andreas
Transform system and the tectonics of California: An alternative
approach. Earth Planet. Sci. Lett., 274, 380-391, 2008.

and uses selected data from the 2007 release of the PBO GPS velocities
(there's now one newer data release). I.e. we used a fairly sparse,
older, but consistent, dataset and the processing (mainly done with
modified GMT tools) goes for smoothness, trying to de-emphasize
potentially spurious gradients.

Cheers


Thorsten



On Thu, 2009-04-02 at 16:26 -0700, David Sandwell wrote:
> Dear All,
>
> In preparation for the upcoming EarthScope meeting we are assembling
> strain rate maps from as many investigators as we can to understand
> the similarities and differences in the various approaches as well as
> to understand the the weaknesses in the underlying GPS array.   The
> plan is to assemble strain rate models and plot them all on the same
> map projection and using the same color scale.   We hope you will
> join us in this comparison.
>
> So if you would like to participate please send strain rate map
> data.  This could be something already published or your latest
> estimates.  The simplest format would be three ascii files containing
> exx, eyy, and exy.  Each file would have lines of  lon, lat, strain.
>
> Corne Kreemer and I will take each file, re-grid using GMT surface,
> and plot the second invariant using a uniform color scale.   We
> assemble the results and distribute to everyone for their comment.
> Finally we will put the results on a poster and present at the
> EarthScope meeting.
>
> David Sandwell
> Corne Kreemer
>
>