Tutorials

Table of Contents

• Layer over half-space model
  • Creating prefix file
  • Creating mesh file
  • Creating configuration file
  • Creating source file
  • Creating receiver file
  • Launching EFISPEC3D
  • Plotting Gnuplot files
  • Visualizing VTK files
• Model including topography
  • Compiling EFISPEC3D tools
  • Creating mesh file
  • Creating configuration file
  • Creating source file
  • Launching EFISPEC3D
  • Visualizing VTK files

Layer over half-space model

This section presents how to prepare and run a simulation using the SCEC model named Layer Over Half-space 1 (LOH.1). See website SEISMOWINE for more information.

Note

Input files are in the directory EFISPEC3D/docs/tutorials/t01/

Once the input files are prepared, go to Launching Simulations to see how to launch the simulation.

See Also

Getting Started to read how to prepare input files.

Creating prefix file

In your simulation directory, create the file "prefix" which contains the prefix of input files

echo "t01" > prefix

Creating mesh file

The mesh is designed to be accurate up to 1 Hz (using Lagrange polynomial of order 4 (mod_global_variables::ig_lagrange_order) and approximately 7 Gauss-Logatto-Legendre nodes at 1 Hz).

Run the journal file t01.jou

path_to_cubit_bash_script/cubit -nogui -nojournal t01.jou

This should create the file t01.inp that contains the mesh of the simulation. To visualise a specific block (such as the absorbing boundary), execute CUBIT command line

draw block 3

Creating configuration file

The configuration file t01.cfg (see below) sets up the general parameters of the simulation:

• The total duration is set to \(20\) s subdivided into \( \Delta t = 3.0e^{-3} \) s to satisfy the Courant–Friedrichs–Lewy condition (CFL condition).
• The receivers time histories are saved every \(10 \Delta t = 3.0e^{-2}\) s.
• The snapshots showing the velocity of particles motion are saved every \(50 \Delta t = 0.15\) s. The receivers used for the snapshots are spaced every \(250\) m.
• The absorbing boundaries are activated. Quadrangle elements used as absorbing boundaries are those defined by CUBIT block named fsu (see CUBIT journal file)
• The medium is defined by two materials whose elastic properties are the shear-wave velocity (vs), the pressure-wave velocity (vp) and the density (rho). The material 1 defines the elastic properties of hexahedron elements grouped inside CUBIT block 1 and so on (see CUBIT journal file).

!*******************************************
!time information
!*******************************************
duration of simulation         = 20.0
time step                      = 3.0e-3

!*******************************************
!receivers' output
!*******************************************
receiver saving increment      = 10

!*******************************************
!snapshot output
!*******************************************
snapshot saving  increment     = 50
snapshot space   increment     = 250.0
snapshot displacement          = .false.
snapshot velocity              = .true.
snapshot acceleration          = .false.

!*******************************************
!boundary absorption information
!*******************************************
boundary absorption            = .true.

!*******************************************
!medium information
!*******************************************
number of material             = 2

material                       = 1
vs                             = 2000.0
vp                             = 4000.0
rho                            = 2600.0

material                       = 2
vs                             = 3464.0
vp                             = 6000.0
rho                            = 2700.0

Creating source file

The SCEC model LOH.1 includes one double couple point source at 2000 meters depth. The file t01.dcs is as follows

    1
  0.0     0.0   -2000.0    5.999     0.0     90.0      0.0     6.0      3.0      8

Note

The source function is a hyperbolic tangent instead of a step exponential as defined by the SCEC model LOH.1

Creating receiver file

The receivers (located on the free surface) are defined by their \(x,y\)-coordinates in the file t01.fsr

  693.0     0.0
  5543.0    0.0
  10392.0   0.0
  490.0     490.0
  3919.0    3919.0
  7348.0    7348.0
  384.0     577.0
  3075.0    4612.0
  5764.0    8647.0

Launching EFISPEC3D

In your simulation directory, execute the command line

mpiexec.hydra -n ncore path_to_EFISPEC3D_binary/efispec3d_1.0_sse.exe

The simulation should run for about 15 min on 2 cores (simulation performed on a laptop with Intel(R) Core(TM) i5-3320M). Increase the number of cores to decrease the computational time.

See Also

Launching Simulations

Plotting Gnuplot files

To plot receivers files *.fsr.*.gpl (or *.vor.*.gpl) created by EFISPEC3D, execute in a gnuplot terminal (at least version 4.4)

a=2
plot "loh3.fsr.000001.gpl" binary format="%10f" u 1:a with line

• a = 2,3,4 corresponds to \(x,y,z\)-displacements, respectively
• a = 5,6,7 corresponds to \(x,y,z\)-velocities , respectively
• a = 8,9,10 corresponds to \(x,y,z\)-accelerations, respectively

See Also

subroutines mod_receiver::init_quad_receiver and mod_receiver::write_receiver_output.

Visualizing VTK files

To vizualize snapshots files *.vts, open the file "t01.collection.snapshot.vxyz.pvd" in Paraview. To visualize peak ground displacement, velocity or acceleration, open the files t01.snapshot.PG*xyz.vts in ParaView.

Model including topography

This tutorial explains how to deform a flat mesh generated by CUBIT with a Digital Elevation Model (DEM).

Note

Input files are in the directory EFISPEC3D/docs/tutorials/t02/

Once the input files are prepared, go to Launching Simulations to see how to launch the simulation.

See Also

Getting Started to read how to prepare input files.

Compiling EFISPEC3D tools

In EFISPEC3D directory, execute the command line

make efispec_tools

This should create the executable EFISPEC3D/bin/cubit_topography.exe

Creating mesh file

1. Create the mesh with a flat free surface by running the journal file t02.jou

   path_to_cubit_bash_script/cubit -nogui -nojournal t02.jou
   

   This should create the file "t02.inp" that contains the mesh with a flat free surface.
2. Deform the mesh with cubit_topography.exe (this program linearly transforms geometric nodes of the file "t02.inp" located between given zmax and zmin according to t02.dem)

   path_to_cubit_topography.exe/cubit_topography.exe t02.inp t02.dem 0.0 -1000.0
   

   This should create the files "t02_topo.jou" and "t02_tmp.inp". The file t02_tmp.inp contains the mesh deformed according to the DEM. However, no absorbing boundary and free surface are defined. To do so, move to step 3 below.
3. Run the CUBIT journal file t02_topo.jou (the journal file imports "t02_tmp.inp" and applies boundary conditions needed by EFISPEC3D.

   path_to_cubit_bash_script/cubit -nogui -nojournal t02_topo.jou
   

   This should create the file "t02_topo.inp" which contains the mesh deformed according to the DEM and the absorbing/free surface boundary conditions. The file "t02_tmp.inp" can be deleted.
4. Replace the file "t02.inp" by "t02_topo.inp"

   mv t02_topo.inp t02.inp
   

Note

.dem file shall have an ESRI ASCII Raster format.

Creating configuration file

The configuration file t02.cfg (see below) sets up the general parameters of the simulation.

!*******************************************
!time information
!*******************************************
duration of simulation         = 20.0
time step                      = 0.5e-3

!*******************************************
!receivers' output
!*******************************************
receiver saving increment      = 20

!*******************************************
!snapshot output
!*******************************************
snapshot saving  increment     = 200
snapshot space   increment     = 100.0
snapshot displacement          = .false.
snapshot velocity              = .true.
snapshot acceleration          = .false.

!*******************************************
!boundary absorption information
!*******************************************
boundary absorption            = .true.

!*******************************************
!medium information
!*******************************************
number of material             = 1

material                       = 1
vs                             = 2000.0
vp                             = 4000.0
rho                            = 2600.0

Creating source file

A double couple point source with a strike of \(15^{\circ}\), a dip of \(70^{\circ}\) and a rake of \(10^{\circ}\) is placed in the middle of the model at 2000 meters depth. The file t02.dcs is as follows

    1
  9600.0   8000.0   -2000.0    3.0    15.0     90.0     10.0     4.0      2.0      8

Launching EFISPEC3D

In your simulation directory, execute the command line

mpiexec.hydra -n ncore path_to_EFISPEC3D_binary/efispec3d_1.0_sse.exe

The simulation should run for about 20 min on 128 cores. Increase the number of cores to decrease the computational time.

See Also

Launching Simulations

Visualizing VTK files

To vizualize snapshots files *.vts, open the file "t02.collection.snapshot.vxyz.pvd" in Paraview. To visualize peak ground displacement, velocity or acceleration, open the files t02.snapshot.PG*xyz.vts in ParaView.