Parameter File

Simulation input parameters

title

Title of the simulation. This is used to identify the simulation in the output files and logs.

Type:

string

Example
title = My cool simulation

NPROC

Number of MPI processors to use for the simulation. This is used to determine the number of processes to spawn for the simulation.

Type:

integer

Example
NPROC = 1

Note

SPECFEM++ currently only supports a single MPI processor. Please set this value to 1.

OUTPUT_FILES

This is the location where the mesher will store all the output files.

Type:

Path as string

Example
OUTPUT_FILES = ./OUTPUT_FILES

Meshing Parameters

PARTITIONING_TYPE

The type of mesh partitioning to use for MPI simulations.

  • SCOTCH: 3

  • METIS: 2

  • INTERNAL (Ascending): 1

Type:

int

Example
PARTITIONING_TYPE = 3

Note

This parameter is only used for MPI simulations and is ignored for serial simulations.

NGNOD

Number of control nodes per element. Supported values: 4 and 9

Type:

int

Example
NGNOD = 9

database_filename

Name of the database file to store the generated mesh.

Type:

string

Example
database_filename = database.bin

Note

The database filename needs to be same in meshing and solver parameter files.

Velocity Models

Velocity models are defined in the meshfem2d module. The velocity model is defined in the model section of the input file. The velocity model is defined by a set of parameters that describe the material properties of the model. An example of a velocity model is shown below:

# number of material systems
nbmodels = 2
# acoustic elastic material system
1 1 2500.d0 3400.d0 1963.d0 0 0 9999 9999 0 0 0 0 0 0
2 1 1020.d0 1500.d0 0.d0 0 0 9999 9999 0 0 0 0 0 0

Note that nbmodels must always be followed by the number of material systems in the model, one for each material system. See paramter descriptions below for more details on the parameters.

Metaparameters

nbmodels

Number of material systems in the model.

Type:

int

Example
nbmodels = 1

TOMOGRAPHY_FILE

Path to an external tomography file for velocity models.

Type:

string

Example
TOMOGRAPHY_FILE = ./DATA/tomo_file.xyz

read_external_mesh

If True the mesh is read from an external file.

Type

logical

Example
read_external_mesh = .true.

Description of material system

Each material system in the model is described by a string.

Note

Only elastic, poroelastic, and acoustic material systems are supported.

Elastic material system

An elastic medium can be described by the following parameters:

  • model_number: integer number to refence the material system

  • rho: density

  • Vp: P-wave velocity

  • QKappa: Attenuation parameter (set to 9999 for no attenuation)

Type:

string

Format:

model_number 1 rho Vp 0 0 QKappa 9999 0 0 0 0 0 0

Example
1 1 2700.d0 3000.d0 1732.051d0 0 0 9999 9999 0 0 0 0 0 0

Acoustic material system

An acoustic medium can be described by the following parameters:

  • model_number: integer number to refence the material system

  • rho: density

  • Vp: P-wave velocity

  • Vs: S-wave velocity

  • QKappa: Attenuation parameter (set to 9999 for no attenuation)

  • QMu: Attenuation parameter (set to 9999 for no attenuation)

Type

string

Format:

model_number 1 rho Vp Vs 0 0 QKappa QMu 0 0 0 0 0 0

Example
1 1 2700.d0 3000.d0 1732.051d0 0 0 9999 9999 0 0 0 0 0 0

Elastic Cosserat material system

An elastic Cosserat medium can be described by the following parameters:

  • model_number: integer number to refence the material system

  • rho: density

  • kappa: P-wave modulus

  • mu: shear modulus

  • nu: Poisson’s ratio

  • j: micro-inertia

Type:

string

Format:

model_number 4 rho kappa mu nu j 0 0 0 0 0 0 0 0 0

Example
1 5 2700.d0 1.0d10 3.0d9 0.25d0 0.1d0 0 0 0 0 0 0 0 0

Poroelastic material system

A poroelastic medium can be described by the following parameters:

  • model_number: integer number to refence the material system

  • rhos: solid density

  • rhof: fluid density

  • phi: porosity

  • c: Biot coefficient

  • kxx: permeability in x direction

  • kxz: permeability in z direction

  • kzz: permeability in z direction

  • Ks: bulk modulus of solid

  • Kf: bulk modulus of fluid

  • Kfr: bulk modulus of fluid in the frame

  • etaf: viscosity of fluid

  • mufr: shear modulus of fluid in the frame

  • Qmu: attenuation parameter (set to 9999 for no attenuation)

Type:

string

Format:

model_number 3 rhos rhof phi c kxx kxz kzz Ks Kf Kfr etaf mufr Qmu

Example
1 3 2650.d0 880.d0 0.1d0 2.0 1d-9 0.d0 1d-9 12.2d9 1.985d9 9.6d9 0.d0 5.1d9 9999

Electromagnetic material system

An electromagnetic medium can be described by the following parameters:

  • model_number: integer number to reference the material system

  • mu0: vacuum permeability

  • e0: vacuum permittivity

  • e11: relative permittivity in 11 direction (multiple of e0)

  • e33: relative permittivity in 33 direction (multiple of e0)

  • sig11: conductivity in 11 direction

  • sig33: conductivity in 33 direction

  • Qe11: electric attenuation in 11 direction

  • Qe33: electric attenuation in 33 direction

  • Qs11: magnetic attenuation in 11 direction

  • Qs33: magnetic attenuation in 33 direction

  • Qv: reserved parameter

Type:

string

Format:

model_number 4 mu0 e0 e11(e0) e33(e0) sig11 sig33 Qe11 Qe33 Qs11 Qs33 Qv 0 0

Example
1 4 12.566d-7 8.85d-12 5 5 2d-3 2d-3 90 90 90 90 0 0 0

Tomography material system

A material defined by external tomography file:

  • model_number: -1 to indicate tomography-based material

  • A: anisotropy flag (for Vs value)

Type:

string

Format:

model_number -1 0 0 A 0 0 0 0 0 0 0 0 0 0

Example
1 -1 0 0 0 0 0 0 0 0 0 0 0 0 0

Note

Material properties will be read from the file specified in TOMOGRAPHY_FILE.

Internal Meshing

interfacesfile

The file describing the topography of the simulation domain. For more information, see the Topography File section.

Type

path as string

Example
interfacesfile = "topography.dat"

xmin

The minimum x-coordinate of the simulation domain.

Type

real

Example
xmin = 0.0

xmax

The maximum x-coordinate of the simulation domain.

Type

real

Example
xmax = 6400.0

nx

The number of elements in the x-direction.

Type:

int

Example
nx = 64

STACEY_ABSORBING_CONDITIONS

If True, Stacey absorbing boundary conditions are used.

Type

logical

Example
STACEY_ABSORBING_CONDITIONS = .true.

absorbbottom

If True, the bottom boundary is an absorbing boundary.

Type

logical

Example
absorbbottom = .true.

absorbtop

If True, the top boundary is an absorbing boundary.

Type:

logical

Example
absorbtop = .true.

absorbleft

If True, the left boundary is an absorbing boundary.

Type:

logical

Example
absorbleft = .true.

absorbright

If True, the right boundary is an absorbing boundary.

Type:

logical

Example
absorbright = .true.

nbregions

The number of regions in the simulation domain.

Type:

int

Example
nbregions = 1

Describing a region

The region is described using a string. And has following parameters:

  • nxmin: Integer value describing the x-coordinate of the spectral element at the bottom left corner of the region.

  • nxmax: Integer value describing the x-coordinate of the spectral element at the top right corner of the region.

  • nzmin: Integer value describing the z-coordinate of the spectral element at the bottom left corner of the region.

  • nzmax: Integer value describing the z-coordinate of the spectral element at the top right corner of the region.

  • material_number: Integer value describing the type of material in the region. This value references the material number in the velocity_model.

Type:

string

Format:

nxmin nxmax nzmin nzmax material_number

Example
0 63 0 63 1

Note

The region description(s) must be preceded by the number of regions in the simulation domain. For example, if there are 2 regions, the file should look like this if you remove comments:

nbregions = 2
0 63 0 30 1
0 63 31 63 2

External Meshing

Parameters here describe the paths to different files generated when using an external mesher.

mesh_file

Path to the mesh file.

Type

path as string

Example
mesh_file = ./DATA/Mesh_canyon/canyon_mesh_file

nodes_coords_file

Path to the file containing the coordinates of the nodes.

Type:

path as string

Example
nodes_coords_file = ./DATA/Mesh_canyon/canyon_nodes_coords

materials_file

Path to the file containing the materials number for each element.

Type:

path as string

Example
materials_file = ./DATA/Mesh_canyon/canyon_materials_file

free_surface_file

Path to the file containing the element number describing the free surface.

Type:

path as string

Example
free_surface_file = ./DATA/Mesh_canyon/canyon_free_surface_file

axial_elements_file

Path to the file containing the element number for elements on the axis.

Type:

path

Example
axial_elements_file = ./DATA/Mesh_canyon/canyon_axial_elements_file

Note

This parameter is not supported in the solver.

absorbing_surface_file

Path to the file containing the element number for elements on the absorbing surface.

Type:

path as string

Example
absorbing_surface_file = ./DATA/Mesh_canyon/canyon_absorbing_surface_file

Note

This parameter is not supported in the solver.

acoustic_forcing_surface_file

Path to the file containing the element number for elements on the acoustic forcing surface.

Type:

path as string

Example
acoustic_forcing_surface_file = ./DATA/Mesh_canyon/canyon_acoustic_forcing_surface_file

Note

This parameter is not supported in the solver.

absorbing_cpml_file

Path to the file containing the element number for elements on the absorbing PML surface.

Type:

path

Example
absorbing_cpml_file = ./DATA/Mesh_canyon/canyon_absorbing_cpml_file

Note

This parameter is not supported in the solver.

tangential_detection_curve_file

Path to the file containing the element number for elements on the tangential curve.

Type:

path as string

Example
tangential_detection_curve_file = ./DATA/Mesh_canyon/canyon_tangential_detection_curve_file

Note

This parameter is not supported in the solver.

Display parameters

output_grid_Gnuplot

Output grid as a Gnuplot file

Type:

logical

Example
output_grid_Gnuplot = .true.

output_grid_ASCII

Output grid as an ASCII file

Type

logical

Example
output_grid_ASCII = .true.

Receiver Parameters

Define meta parameters

use_existing_STATIONS

If set to .true., the receivers will be places based on an existing STATIONS file.

Type:

logical

Example
use_existing_STATIONS = .false.

nreceiversets

Number of receiver sets.

Type:

int

Example
nreceiversets = 1

anglerec

Angle to rotate components at receivers

Type:

real

Example
anglerec = 0.0d0

rec_normal_to_surface

If set to .true., the receiver base angle will be set normal to the surface. Requires external mesh and tangential curve file.

Type:

logical

Example
rec_normal_to_surface = .false.

Note

This paramter is not supported yet in the solver.

Define receiver sets

Next we define each receiver sets using the following parameters:

nrec

Number of receivers in this set. The receivers will be placed at equal distances.

Type

int

Example
nrec = 10

xdeb

X coordinate of the first receiver in this set.

Type:

real

Example
xdeb = 0.0d0

zdeb

Y coordinate of the first receiver in this set.

Type:

real

Example
zdeb = 0.0d0

xfin

X coordinate of the last receiver in this set.

Type:

real

Example
xfin = 6400.0d0

zfin

Z coordinate of the last receiver in this set.

Type:

real

Example
zfin = 0.0d0

record_at_surface_same_vertical

If set to .true., the receivers will be placed at the surface of the medium. The vertical position of the receivers will be replaces with topography height.

Type:

logical

Example
record_at_surface_same_vertical = .false.

stations_filename

Name of the STATIONS file to use. if use_existing_STATIONS is set to .true., this defines a file to read receiver locations from. If use_existing_STATIONS is set to .false., this defines a file to write receiver locations to.

Type:

string

Example
stations_filename = stations.dat