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DocumentationPreparationIntroduction

Introduction

In this section, we will introduce how to prepare data, mesh, model, parameters, and input files before SpecFWAT.

Required Files and Directories


fwat_data/

This directory contains the seismic data, which is used for the forward simulation and adjoint measurements.

DATA/meshfem3D_files/

This directory contains the mesh files (Following Specfem3D format), which define the computational domain for the forward simulation.

DATA/tomo_files/tomography_model.h5

This file contains the initial model parameters in HDF5 format, which is used for creating GLL mesh and defining the model databases for the forward simulation.

DATA/fwat_params.yml

This file contains the parameters for the SpecFWAT workflow.

DATA/Par_file

This file contains the parameters for the Specfem3D. See Main parameter file Par_file section in the Specfem3D documentation  for more details.

src_rec/

This directory contains the source and receiver files, which define the source and receiver locations and porperties.

Glossary

The SpecFWAT has a few key terms that are used throughout the documentation. Some values of these keys are used as the command line arguments for the SpecFWAT executables and used to define suffixes of input and output files. The following is a list of the key terms and their meanings:

1. simu_type

The simu_type is a key term that defines simulation type. It can take the following values:

  • noise
  • tele
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The simu_type will be used in following cases:

  • As a command line argument -s after the xfwat_mesh_databases and xfwat_fwd_measure_adj.
  • For joint inversion, as a suffix to define the path of databases and sum of kernels .
    • The database path will be {LOCAL_PATH}/{simu_type}
    • The sum of kernels will be output/SUM_KERNELS_{simu_type}

The LOCAL_PATH is the parameter defined in Par_file.

2. dat_type

The dat_type is a key term that defines the data type for the source and receiver files. It can take the following values:

For simu_type = noise
  • noise: Ambient noise data
For simu_type = tele
  • tele: Teleseismic waveform
  • rf: Receiver function waveform
  • telecc: Teleseismic cross-convolution
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The dat_type will be used to define the suffix of source list file in src_rec/ directory, such as sources_noise.dat, sources_tele.dat, sources_rf.dat, and sources_telecc.dat.

For teleseismic FWAT, the TELE_TYPE in fwat_params.yml will be used to define the dat_type for the source list files. See teleseismic parameters for more details.

3. model

The model is a key term to define model name of each iteration in the inversion process. It is usually a string with the format MXX, where XX is two-bit integer number representing the iteration number. For example, M00, M01, …, M09.

4. event_name

The event_name is a key term to define the event name for each seismic event. It is usually a string with unique identifier for each event. For ambient noise data, It could be the virtual source name (station name) such as KW.MX001. For teleseismic data, it could be the event name such as 20210101_123456.

The event_name will be used to define:

  • Observed data folder fwat_data/${event_name}/
  • Source file name FORCESOLUTION_${event_name} for ambient noise tomography in src_rec/ directory
  • FK model file name FKmodel_${event_name} for teleseismic tomography in src_rec/ directory
  • Station file name STATIONS_${event_name} in src_rec/ directory

Project Structure

The project is a work directory organized based on Specfem3D. Thus, subdirectories of Specfem3D are inherited in SpecFWAT. Usually we conduct an inversion and execute all scripts and commands in this directory. New directories of input files fwat_data and src_rec are added to the SpecFWAT project. The following is a brief description of the directory structure of a project:

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