[CIG-SHORT] reg: RELAX run

[Sylvain Barbot]

Dear Anil,

The coordinates system in Relax is not the same as for GMT. The
directions 1, 2 and 3 in Relax are for north, east and depth,
respectively. This is to obtain a right-handed coordinate system. So
your scripts will work if you switch the first two coordinates.

I have converted the coseismic slip model of Chlieh et al. (2007).
They use patches of 20x16km (you seem to use incorrectly 15x12 km).
Before running lengthy computations, you can always verify the
geometry of your slip model using

flt2vtk.sh

for example,

flt2vtk.sh < anda.flt > anda.vtp

which converts the slip model into a Paraview file. To check with the
coast lines, you can use

xyz2vtk.sh

with the .xyz file you generated with pscoast. For example,

xyz2vtk.sh < coasts_km.xyz > coasts_km.vtp

and then load in Paraview. I attach both files for reference.

I have added the Aceh 2004 earthquake as an example in the repository
and you may access it there. If you downloaded the most up-to-date
sources with

hg clone http://geodynamics.org/hg/short/3D/relax relax

then you can get the new examples with the commands

hg pull
hg update

In your Relax input file, you also use a sampling size of 16 km, which
is insufficiently small to resolve 16x20 km patches. I suggest using a
sampling of 4 km and a 1024x1024x512 grid, if you have enough RAM to
do so.

Best wishes,
Sylvain



2012/10/13 Anil Earnest <earnest at cmmacs.ernet.in>:
> Hi,
>      I was trying to do a co-seismic simulation using RELAX for the 2004
> Sumatra-Andaman earthquake. Issue is that the simulated rupture
> segments are coming on diagonally opposite quadrant than expected.
> Could you please help me in resolving this. Attaching the
> visualization as a pdf file.
>
> Thanks in advance.
>
> - Anil Earnest
>
>  I took slip-data from:
> http://www.tectonics.caltech.edu/slip_history/2004_sumatra/update1/slipAceh_BSSA2007
>
> Based on the RELAX examples;
>
> Reformatted the above fault geometry as:
> awk '{print $1, $2, $3, $4, $5, $6, $7}' slipAceh_BSSA2007 | awk '{if
> (substr($0,0,1)==">"){print "#"}else{print $0}}' | proj +proj=utm +zone=46
> +datum=WGS84 +geoc |  awk '{print(NR,
> $3,($1-817174.63)/1e3,($2-369446.69)/1e3,$7,15,12,$5,$6,$4)}' > anda.flt
>
> for coast-lines I used:
>  pscoast -R90/100/0/20 -JM -Df -W1 -m | proj +proj=utm +zone=46
> +datum=WGS84 +geoc | awk '{if (substr($0,0,1)==">"){print "#"}else{print
> $0}}' | awk '{if (substr($0,1,1)=="*"){print ">"}
> else{x=($1-817174.63)/1e3;y=($2-369446.69)/1e3;print x,y,0}}' >
> coasts_km.xyz
>
> and ran using the following script:
>
> #/bin/bash
>
> # Mw 9.2 2004 Sumatra-Andaman earthquake coseismic displacements
> #
> # echo 95.854 3.316 | proj +proj=utm +zone=46 +datum=WGS84 +geoc
> # 817174.63     369446.69
> #
> FLT=faults/anda.flt
> #
> # output directory based on script name.
> WDIR=$(basename $0 .sh)
>
> if [ ! -e $WDIR ]; then
>         echo $(basename $0): creating directory $WDIR
>         mkdir $WDIR
> fi
>
> OMP_NUM_THREADS=4 time relax $* <<EOF | tee $WDIR/in.param
> # grid dimension (sx1,sx2,sx3)
> 512 512 512
> # sampling (dx1,dx2,dx3), smoothing (beta, nyquist)
> 16 16 4 0.2 1
> # origin position (x0,y0) and rotation
> 0 0 0
> # geographic origin (longitude, latitude, UTM zone, unit)
> 95.854 3.316 46 1e3
> # observation depth (displacement and stress)
> 0 15
> # output directory
> $WDIR
> # lambda, mu, gamma (gamma = (1 - nu) rho g / mu)
> 1 1 1e-5
> # time interval, (positive time step) or (negative skip, scaling)
> 0 -1 1
> # number of observation planes
> 0
> # number of observation points
> 0
> # number of Coulomb planes
> 0
> # number of prestress interfaces
> 0
> # number of linear viscous interfaces
> 0
> # number of nonlinear viscous interfaces
> 0
> # number of fault creep interfaces
> 0
> # number of inter-seismic strike-slip segments
> 0
> # number of inter-seismic opening segments
> 0
> # number of events
> 1
> # number of coseismic shear-slip segments (ns)
> `grep -v "#" $FLT | wc`
> # no.     slip       xs       ys       zs  length   width strike   dip   rake
> `grep -v "#" $FLT`
> # number of tensile cracks
> 0
> # number of mogi source
> 0
> # number of surface traction
> 0
> EOF
>
> -------
>
> visualized using :
> grdmap.sh -b -750/1550/-550/1300 -e gmt/ecoast.sh coseismic/000
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