Horizontal Cross-Section of Strike-Slip Fault (2D)

The files are in the directory examples/strikeslip-2d. The files and directories for this set of examples includes:

README.md:

README file containing a brief description of the various examples.

*.cfg:

PyLith parameter files.

generate_gmsh.py:

Python script to generate the finite-element mesh using Gmsh.

*.msh:

Gmsh finite-element mesh files generated by Gmsh.

*.jou:

Files used to construct the finite-element mesh using Cubit.

*.exo:

Exodus II finite-element mesh files generated by Cubit.

*.spatialdb:

Spatial database filesFiles associated with the spatial databases.

viz:

Directory containing ParaView Python scripts and other files for visualizing results.

output:

Directory containing simulation output. It is created automatically when running the simulations.

Overview

This suite of examples demonstrates some basic concepts of using PyLith to solve the static and quasistatic boundary elasticity equation for a horizontal cross-section of a strike-slip fault (Fig. 48) with nonuniform material properties. The fault extends the entire length of the domain. The shear modulus is larger on the +x side of the fault. This example builds on the previous examples and adds complexity through a series of steps:

Step 1:

Static coseismic slip with Dirichlet (displacement) boundary conditions.

Step 2:

Quasistatic coseismic slip with time-dependent Dirichlet (displacement) boundary conditions.

Step 3:

Quasistatic slip with two ruptures and time-dependent Dirichlet (displacement) boundary conditions.

Step 4:

Variable slip and Dirichlet (displacement) boundary conditions.

Step 5:

Static Green’s functions with Dirichlet (displacement) boundary conditions.

Step 6:

Invert for slip in Step 4 using Green’s functions from Step 5 and least squares.

Step 7:

Invert for slip in Step 4 using Green’s functions from Step 5 and the CATMIP Bayesian framework.

Fig. 48 Diagram of geometry for domain with a strike-slip fault. The domain extends from -50 km to +50 km in the x direction and from -75 km to +75 km in the y direction. We refer to the domain boundaries using the names shown in the diagram.

Important

We decribe how to generate the finite-element mesh using both Gmsh and Cubit. The files for both methods are included. For Step 1 we provide PyLith parameter files for both meshes; for Steps 2 and 3 we only provide the Parameter files that use the Gmsh file.

Example Workflow

• Gmsh Mesh
  • Geometry
  • Meshing using Python Script
• Cubit Mesh
  • Geometry
  • Meshing using Journal Scripts
• Common Information
  • Metadata, Mesh, and Output
  • Physics
• Step 1: Static Coseismic Slip
  • Simulation parameters
  • Running the simulation
  • Visualizing the results
  • Step 1 with Cubit Mesh
• Step 2: Single Earthquake Rupture and Velocity Boundary Conditions
  • Simulation parameters
    • Boundary conditions
  • Running the simulation
  • Visualizing the results
• Step 3: Multiple Earthquake Ruptures and Velocity Boundary Conditions
  • Simulation parameters
  • Running the simulation
  • Visualizing the results
• Step 4: Variable Coseismic Slip
  • Simulation parameters
  • Running the simulation
  • Visualizing the results
• Step 5: Green’s Functions
  • Simulation parameters
  • Running the simulation
  • Visualizing the results
• Step 6: Least Squares Fault Slip Inversion
  • Plotting the results
• Step 7: Bayesian Fault Slip Inversion
  • Inversion using original CATMIP algorithm
    • Step 7a: Plotting the results
• Suggested Exercises