<div dir="ltr">Dear Shannon,<div><br></div><div>The convention for the input and output of Relax is to use the coordinate system (x1,x2,x3) where x1 is for north, x2 for east and x3 for depth - unless mentioned otherwise. This is a right-handed coordinate system. The .grd files have a more explicit name</div>
<div><br></div><div>000-north.grd</div><div>000-east.grd<br></div><div>000-up.grd<br></div><div><br></div><div>and 000-up.grd is positive for upwards displacement. So if everything is working well values in 000-up.grd and the GPSX.txt files should have an opposite sign. So this is not a bug! </div>
<div><br></div><div>If you want to use a positive value for upwards movement, you should multiply the GPS output files by -1 in the vertical direction.</div><div><br></div><div>Best wishes,</div><div>Sylvain</div></div><div class="gmail_extra">
<br><br><div class="gmail_quote">2013/10/6 Shannon Graham <span dir="ltr"><<a href="mailto:segraham@geology.wisc.edu" target="_blank">segraham@geology.wisc.edu</a>></span><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div style="word-wrap:break-word"><div><br></div><div>Hello,</div><div><br></div><div>I was wondering if anyone has encountered an error in the sign of vertical displacements predicted for a GPS site (in the GPS.txt file) by RELAX? For example for a simple coseismic slip model, an Okada solution predicts uplift for a given point, using gmt's grd2xyz on the 000-up.grd file shows that RELAX predicts uplift for the given point. However, the GPS.txt file output by RELAX shows subsidence of the same magnitude. Horizontal offsets match for all three. All of the predicted coseismic offsets have been validated for this model with an Okada solution (compared against a grd2xyz on the 000-{east, north, or up}.grd files). Is the incorrect sign due to depths listed as positive, such that uplift would receive the opposite sign? </div>
<div><br></div><div>Example:</div><div>Okada easting northing East disp North disp Vertical disp</div><div>
</div><div>
<table border="0" cellpadding="0" cellspacing="0" width="375" style="border-collapse:collapse;width:375pt">
<colgroup><col width="75" span="5" style="width:75pt">
</colgroup><tbody><tr height="13" style="height:13.0pt">
<td height="13" align="right" width="75" style="height:13.0pt;width:75pt">-3</td>
<td align="right" width="75" style="width:75pt">-6</td>
<td align="right" width="75" style="width:75pt">-7.75E-03</td>
<td align="right" width="75" style="width:75pt">-1.32E-02</td>
<td align="right" width="75" style="width:75pt">3.46E-02</td>
</tr>
</tbody></table>Relax grd2xyz</div><div>
<table border="0" cellpadding="0" cellspacing="0" width="375" style="border-collapse:collapse;width:375pt">
<colgroup><col width="75" span="5" style="width:75pt">
</colgroup><tbody><tr height="13" style="height:13.0pt">
<td height="13" align="right" width="75" style="height:13.0pt;width:75pt">-3</td>
<td align="right" width="75" style="width:75pt">-6</td>
<td align="right" width="75" style="width:75pt">-0.007753871</td>
<td align="right" width="75" style="width:75pt">-0.01320722</td>
<td align="right" width="75" style="width:75pt">0.034613539</td>
</tr>
</tbody></table>Relax GPS.txt</div><div>
<table border="0" cellpadding="0" cellspacing="0" width="375" style="border-collapse:collapse;width:375pt">
<colgroup><col width="75" span="5" style="width:75pt">
</colgroup><tbody><tr height="13" style="height:13.0pt">
<td height="13" align="right" width="75" style="height:13.0pt;width:75pt">-3</td>
<td align="right" width="75" style="width:75pt">-6</td>
<td align="right" width="75" style="width:75pt">-7.75E-03</td>
<td align="right" width="75" style="width:75pt">-1.32E-02</td>
<td align="right" width="75" style="width:75pt">-3.46E-02</td>
</tr>
</tbody></table><br></div><div>Thank you in advance for any help and suggestions!</div><div>Shannon Graham</div><div><br></div><div>relax input file of reference:</div><div><div>#/bin/bash</div><div><br></div><div># output directory based on script name.</div>
<div>WDIR=test_defmod_10km_ny_dx_Jal</div><div><br></div><div>if [ ! -e $WDIR ]; then</div><div><span style="white-space:pre-wrap"> </span>echo $(basename $0): creating directory $WDIR</div><div><span style="white-space:pre-wrap"> </span>mkdir $WDIR</div>
<div>fi</div><div><br></div><div>time relax --no-proj-output $* <<EOF | tee $WDIR/in.param</div><div># grid dimension (sx1,sx2,sx3)</div><div>512 512 512</div><div># sampling (dx1,dx2,dx3), smoothing (beta, nyquist)</div>
<div>3 3 3 0.2 5</div><div># origin position (x0,y0) and rotation</div><div>0 0 0</div><div># geographic origin (longitude, latitude, UTM zone, unit)</div><div>#-147.73 61.04 6 1e3</div><div># observation depth (displacement and stress)</div>
<div>0 5</div><div># output directory</div><div>$WDIR</div><div># lambda, mu, gamma (gamma = (1 - nu) rho g / mu)</div><div>30 30 1e-5</div><div># time interval, (positive time step) or (negative skip, scaling)</div><div>
0 -1 1 </div><div># number of observation planes</div><div>0 </div><div># number of observation points</div><div>2</div><div># no name x1 (north) x2 (east) x3(depth)</div><div>1 G001 -6.0 -3.0 0.0</div><div>2 G002 -3.0 0.0 0.0 </div>
<div># number of Coulomb planes</div><div>0</div><div># number of prestress interfaces</div><div>0</div><div># number of linear viscous interfaces</div><div>0</div><div># number of nonlinear viscous interfaces</div><div>0</div>
<div># number of fault creep interfaces</div><div>0</div><div># number of inter-seismic strike-slip segments</div><div>0</div><div># number of inter-seismic opening segments</div><div>0</div><div># number of events</div><div>
1</div><div># number of coseismic shear-slip segments (ns)</div><div>1</div><div># no. slip xs ys zs length width strike dip rake</div><div>01 1.0 -3.0783 3.94 20 10 10 308 30 90</div><div>
# number of tensile cracks </div><div>0</div><div># number of mogi source</div><div>0</div><div># number of surface traction</div><div>0</div><div>EOF</div></div><div><br></div><div><br></div></div><br>_______________________________________________<br>
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