Name of program: "Virtual_California"

Type of program (eg quake model, mesh generator, strain calculator, visualizer, etc):

Realistic earthquake simulation.

Group of codes based upon a CA model of an arbitrary, 3-D, driven vertical strike slip fault system in an elastic layer overlying a Maxwell viscoelastic half space. Generates synthetic earthquake histories using quasistatic CA-type friction law. From these, both horizontal components of surface deformation and horizontal strain can be calculated. These simulations can be used to develop earthquake pattern recognition algorithms, test ideas about the physics of earthquakes, or other developmental activities.

Author: JB Rundle

Institution: University of Colorado

Program's heritage (ie name and author of predecessor code if any): None

Actively being further developed (y/n): Y

Language: Fortran 77

2d (y/n):

3d (y/n): 2 1/2 dimensions...no vertical displacements, but arbitrary 3-D Geometry

Elastic full space (y/n):

Elastic half space (y/n):

Layered elastic (y/n):

Viscoelastic half space (y/n):

Layered viscoelastic (y/n): Elastic Layer over Viscoelastic Half Space

Maximum number of faults: In principle, unlimited..version in ftp area has 160 segments

Forward model (y/n): Y

Inversion capability (y/n): N

Type of inversion:

Finite element ability (y/n): N -- Boundary element

Boundary constraints:

Automatic mesh generation:

Includes self gravitation (y/n): N

Quasi-static failure criteria (y/n): Y -- CA type dynamics

User defined failure criteria (y/n): Y

Hardwired failure criteria (eg Coulomb): Coulomb

Dynamic solution (y/n): N

Includes waves (y/n): N

Highest resolved frequency:

Includes inertia (y/n): N

Are there accompanying utilities (y/n): Y

Is it one main program or several programs that communicate via scripts, files, and pipes? Many programs that communicate via files

If it is several programs, please give a 1 line description of the major players.

Please refer to README file in ftp area for complete instructions

1. editfric.f -- edits fault friction file. Example is friction_file.f
2. editfault.f -- edits fault geometry file. Example given is sc803018_faults.d
3. Sequence of computations:
   1. Run stress_coefficients.f on fault gemetry file. Produces an output file. Example input is sc803018_faults.d, output is sc803018_98.d.
   2. Then run adjust.f to compress it. Example input is sc803018_98.d, output is sc803018_98.out.
   3. This file is then used as input to the simulation code, earthquake_synthesizer.f The output is a data file with the synthetic events in it. Example given is synthetic_events.d
   4. Simulate earthquakes can be visualized using the IDL code Quake_Plot.pro and its dependent procedures, *.pro Examples of output visualization from the file synthetic_events.d are given as *.ps files
   5. For computation of surface deformation, use the file deformation-vectors.f on the fault geometry file...this computes the deformation Green's functions. Example of these Green's functions is deformation-vecs.out.
   6. Then use Quake_Plot.pro to visualize vectors (it uses the procedure dispvecs.pro). Example of .ps output is deformation-vecs.ps

Input format description: See ftp site

Output format description: See ftp site

Is this code available to interested researchers (y/n): Y

Executable available (y/n): N...needs to be simply compiled using F77

Type of machine: SUN

Source available (y/n): Y They are available at: ftp: fractal.colorado.edu/~pub/Viscocodes/Virtual_California

Please describe what you consider to be the important features of this code in a paragraph or two.

Complete description can be found in the references below and the ftp site.

This is the only code that I know that has ever been written that uses arbitrary 3-D rectangular faults in elastic layer over viscoelastic half space to produce realistic complete simulations of stress and deformation for arbitrary fault geometries. All other codes are either planar faults only, elastic only, do not allow arbitrary fault properties, cannot simulate arbitrary specified geometries, and so forth.

Note that these codes are under active development. Developmental versions of new codes that incorporate the possibility of precursory slip and aftershocks, together with better computations of interaction coefficients are available at:

hopfield.colorado.edu/rundle/FEYNMAN

However, these latter are at the moment undocumented, although they will be documented and published in the future.

References describing the algorithms or results from use:

JBR, A physical model for earthquakes, 1., Fluctuations and interactions, Jour. Geophys. Res., 93, 6237-6254, 1998)

JBR, A physical model for earthquakes, 2., Application to Southern California, Jour. Geophys. Res., 93, 6255-6274, 1988)