[cig-commits] commit: update the documentation to include the Sunda 3d viscoelastic structure.
Mercurial
hg at geodynamics.org
Fri Dec 21 20:29:52 PST 2012
changeset: 163:209030c2508e
tag: tip
user: Sylvain Barbot <sbarbot at caltech.edu>
date: Fri Dec 21 20:29:40 2012 -0800
files: latex/graphics/sunda.jpg latex/relax.tex
description:
update the documentation to include the Sunda 3d viscoelastic structure.
diff -r 926a8451e67c -r 209030c2508e latex/graphics/sunda.jpg
Binary file latex/graphics/sunda.jpg has changed
diff -r 926a8451e67c -r 209030c2508e latex/relax.tex
--- a/latex/relax.tex Fri Dec 21 19:58:22 2012 -0800
+++ b/latex/relax.tex Fri Dec 21 20:29:40 2012 -0800
@@ -364,7 +364,55 @@ Let's look at how to define a viscosity
{\color{orange} 1 -1 0 0 10 200 5 200 90 90}
...
\end{alltt}
-We then add a large volume abutting the center of the computational volume, where we modify the fluidity from $\dot{\gamma}_0=1\,$yr$^{-1}$ to $\dot{\gamma}_0=0$, using $\Delta\dot{\gamma}_0=-1\,$yr$^{-1}$. As a null fluidity corresponds to elastic behavior, the brittle-ductile transition occurs 5\,km deeper going west to east across the $x_1$ (north-south) axis. The geometry of a slab can be obtained by modifying the strike and dip angles. Changing the strike of the ductile zone from 90 to 0$^\circ$ would make the transition occur from south to north. If the background and anomalous fluidities add to a negative, unphysical, value, the sum is corrected to null, and the result is an effective elastic property. Realistic structures can be accounted for from structural data using a large quantity of ductile anomalies tuned to observations.
+We then add a large volume abutting the center of the computational volume, where we modify the fluidity from $\dot{\gamma}_0=1\,$yr$^{-1}$ to $\dot{\gamma}_0=0$, using $\Delta\dot{\gamma}_0=-1\,$yr$^{-1}$. As a null fluidity corresponds to elastic behavior, the brittle-ductile transition occurs 5\,km deeper going west to east across the $x_1$ (north-south) axis. The geometry of a slab can be obtained by modifying the strike and dip angles. Changing the strike of the ductile zone from 90 to 0$^\circ$ would make the transition occur from south to north. If the background and anomalous fluidities add to a negative, unphysical, value, the sum is corrected to null, and the result is an effective elastic property.
+
+Realistic structures can be accounted for from structural data using a large quantity of ductile anomalies tuned to observations. Consider the case of the Sunda subduction slab where the top of the elastic slab is described by a series of fault segments:
+\begin{alltt}
+# no x1 x2 x3 length width strike dip rake
+001 -1008.183459 976.507098 8.540000 50.000000 50.094787 -53.290307 3.525208 76.733951
+002 -969.881237 944.367717 8.922983 50.000000 50.089914 -51.101544 3.433540 78.917890
+003 -931.579015 912.228337 9.414930 50.000000 50.131393 -50.400541 4.149189 79.626125
+004 -893.276793 880.088956 10.365896 50.000000 50.219974 -48.252647 5.364677 81.783007
+005 -854.974571 847.949576 11.813879 50.000000 50.404913 -46.965533 7.267302 83.089879
+006 -816.672349 815.810195 11.651879 50.000000 50.416558 -46.119837 7.370354 83.930348
+007 -778.370126 783.670815 11.301228 50.000000 50.406643 -44.084141 7.282706 85.948697
+008 -740.067904 751.531434 11.463158 50.000000 50.410988 -41.986592 7.321244 88.029592
+009 -701.765682 719.392054 11.242973 50.000000 50.406957 -40.363071 7.285500 89.639860
+010 -663.463460 687.252674 10.615908 50.000000 50.373596 -40.351118 6.982417 89.651486
+011 -625.161238 655.113293 10.455476 50.000000 50.350356 -40.820083 6.763064 89.185623
+...
+\end{alltt}
+which is saved in the file \verb'sunda.flt'. A three-dimensional model of the elastic slab can be constructed by extending the fault segments into volumes. Lets consider a 80\,km thick slab. We start with a depth-dependent model with visco-elastic relaxation below 80\,km:
+\begin{alltt}
+# number of linear viscous interfaces for elastic plate
+{\color{orange}1}
+# no depth gammadot0 cohesion
+{\color{orange} 1 80.0 1.0 0.0}
+# number of linear ductile zone
+{\color{orange}0}
+\end{alltt}
+and let's add the down-going slab:
+\begin{alltt}
+# number of linear viscous interfaces for elastic plate
+{\color{orange}1}
+# no depth gammadot0 cohesion
+{\color{orange} 1 80.0 1.0 0.0}
+# number of linear ductile zone
+{\color{orange}`grep -v "#" sunda.flt | wc`}
+# nb dgammadot0 x1 x2 x3 length width thickness strike dip
+{\color{orange}`grep -v "#" sunda.flt | awk '{print NR,-10,$2,$3,$4,$5,80,$6,$7,$8+90}'`}
+...
+\end{alltt}
+The last line creates a list of blocks extending the slab interface down and reducing the fluidity by a large number ($-10\,$yr$^{-1}$) to set the fluidity to 0 and the viscosity to infinity. The slab geometry is shown in Fig.~\ref{fig:sunda}.
+
+%
+\begin{figure*}[h]
+\centering
+\includegraphics[width=\textwidth]{sunda.jpg}
+\caption{\small Three-dimensional viscoelastic structure for the Sunda down-going slab. The opaque interface represent an elastic lithosphere extended at depth by the cubic boxes (ductile zones). The mantle wedge is below Sumatra.}
+\label{fig:sunda}
+\end{figure*}
+%
@@ -733,7 +781,7 @@ and shows a monotonic decrease of the po
The directory \verb'examples' contains a comprehensive list of input files with published slip distributions of recent earthquakes. The database includes the case of the 1999 M$_w$ 7.6 Chi-Chi~\citep{johnson+01}, the 1964 M$_w$ 9.2 Alaska~\citep{johnson+96}, the 1992 M$_w$ 7.3 Landers~\citep{fi04c}, 1999 M$_w$ 7.1 Hector Mine~\citep{si+02a}, the 2012 Canterbury (New Zealand)~\citep{elliott+12}, the 2004 M$_w$ 6.0 Parkfield~\citep{bruhat+11}, the 2001 M$_w$ 7.8 Kokoxili (Tibet)~\citep{lasserre+05,ryder+11}, the 2010 M$_w$ 6.8 Yushu (Tibet)~\citep{li+11}, the 2008 M$_w$ 7.1 Yutian (Tibet)~\citep{elliott+10} earthquakes, organized by geography. New slip distributions will continue to be included and placed in this repository.
-The utility \verb'util/flt2vtk.sh' transforms the slip distribution in the Paraview format for visualization in three dimensions.
+The utility \verb'util/flt2vtk.sh' transforms the slip distribution in the Paraview format for visualization in three dimensions, for example the 1964 M$_w$ 9.2 Alaska slip model in Fig.~\ref{fig:alaska}.
%
\begin{figure*}[h]
@@ -791,6 +839,8 @@ Some other files only contain geometrica
\verb'aplane-0001.vtp' & Paraview file for the afterslip plane number 1\\
\verb'linearlayer-001.vtp' & Paraview file for depth of the first linear viscosity change\\
\verb'cgrid.vtp' & Paraview file for extent of the computational domain\\
+\verb'weakzones-linear.vtp' & Paraview file for all linear ductile zones\\
+\verb'weakzones-nonlinear.vtp' & Paraview file for all nonlinear ductile zones\\
\verb'time.txt' & time associated with time step\\
\end{tabular}\\
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