Adjoint-state Traveltime Tomography (Trainning Version)

The code is for adjoint-state traveltime tomography (ATT) in the Cartesian coordinates. This simple version is mainly for training purpose.

The details of the algorithm can be found at Tong, P. (2021). Adjoint-state traveltime tomography: Eikonal equation-based methods and application to the Anza area in southern California. Journal of Geophysical Research: Solid Earth, 126, e2021JB021818. https://doi.org/10.1029/2021JB021818.

Requirements

In order to run the codes, you have to install GNU Fortran [Operating system setup tutorials in Chinese]:

# Fedora
$ sudo dnf install gcc-gfortran
    
# CentOS
$ sudo yum install gfortran
    
# Ubuntu/Debian
$ sudo apt install gfortran
    
# macOS
$ brew install gfortran

Generic Mapping Tools (GMT) is used to plot figures. Refer to [GMT reference book in Chinese] for GMT installation and usage.

Part I: Data

$ cd data

Prepare your data in dataInFormat_D_xyz following the designed format. I use syntheticData.f90 to generate synthetic earthquakes and seismic stations.

$ cd dataSelection/0_commandCenter/

Set the parameters in parametersData.F90. You can select the regions for earthquakes and seismic stations. The two regions can be different.

$ ./workflowStep.sh

Part II: CommandCenter

$ cd ../../../commandCenter

You should have the following files ready at ../data/:

1. sources
2. receivers
3. nevtstaray
4. evtstaminmax
5. traveltimeReceiverGathers

Set the parameters in parametersGenerator.F90. The dimension of the forward grid, number of multiple grids, iteration number and some others can be defined here. You can compile and execute parametersGenerator.F90 at this time.

$ gfortran -o xpara parametersGenerator.F90
$ ./xpara
$ rm xpara

Part III: Model

cd ../model

If this is for a recovery test, you can set up the target velocity model by editing velocity3d_true.F90.

$ gfortran -o xvel velocity3d_true.F90
$ ./xvel
$ rm xvel

Otherwise, just define the initial model for seismic tomography by editing velocity3d.F90.

$ gfortran -o xvel velocity3d.F90
$ ./xvel
$ rm xvel

Part IV: Mesh

cd ../mesh

Edit memeshgenerator.F90 to adjust the size of the inversion grid. The following three parameters should be properly set.

invx = 12
invy = 3
invz = 11

In general, we sample one-wavelength anomaly by 5 grid points or the grid interval is about one fourth of the anomaly wavelength.

$ gfortran -o xmesh meshgenerator.F90
$ ./xmesh
$ rm xmesh regmesh.mod

Part V: CommandCenter

cd ../commandCenter

# Run it if this is a recovery test
$ ./workflow_obstime.sh

$ ./workflow_inversion.sh

The obtained velocity model is located at ../inversion/ as velocity3d015.

Part VI: Figure

You can display the results along the cross-section set by lineEnds:

$ ./plot-cross-section.sh

The Bash script will call zCutVelocity.f90 and the gmt script vcut.gmt.