Choose a backend#

Choose the physical formulation and observable before choosing numerical settings. Every tutorial below contains a complete build/read/plot script.

Backend	Formulation and use	Main reader outputs
QSEIS2025	Layered half-space; dynamic waveforms with direct tensor/rotation outputs	Displacement, velocity, acceleration, strain/stress and rates, rotation and rate, volume
QSEIS06 (deprecated)	Layered half-space; established vector waveform workflow	Displacement, velocity, acceleration; separate derivative-library tools
SPGRN2012 (deprecated)	Spherical layered Earth; reduced-time waveform library	Displacement, velocity, acceleration
SPGRN2020	Spherical layered Earth; windows tied to direct P onset	Displacement, velocity, acceleration
QSSP2020	Spherical layered Earth with optional self-gravitation and broad observables	Vector, tensor, rotation and gravity families; see conversion limitation
EDGRN → EDCMP	Layered elastic half-space; static dislocation response	Displacement, strain, stress and tilt

QSEIS2025 is the recommended first tutorial. QSEIS06 and SPGRN2012 are deprecated in pygrnwang. Use QSEIS2025 for new layered half-space calculations and SPGRN2020 for new spherical waveform libraries. The deprecated backends and their tutorials remain available for existing workflows. When migrating, rebuild the library and validate the model, sampling, source time function and time origin with the replacement backend.

Shared tutorial setup#

From a checkout root, install the package and plotting dependency, then run a tutorial with the active Python environment:

python -m pip install -e .
python -m pip install matplotlib
python examples/qseis2025.py

Use installation for wheels and platform requirements. A source/editable installation requires gfortran. The scripts require the compiled executables from the package and write only to their output directories.

All scripts support --output-dir PATH and --reuse. The default is examples/output/<backend>. A successful run writes disp.npz, disp.png, summary.json and a library/ directory; QSEIS2025’s tensor option adds strain/stress arrays and figures. Scripts check shape, finiteness and nonzero response. The common helpers are documented in model preparation.

Tutorial physics is explicit: a 10 km source, surface receiver, 30° azimuth, strike/dip/rake 30°/45°/90°, and moment 10^15 N m. Elastic velocities and density come from the bundled AK135 model; attenuation is the illustrative constant Qp=600, Qs=300, not AK135-F attenuation. QSEIS/EDGRN use the first 24 numeric model rows (to 809.5 km); spherical examples use the full Earth. EDGRN additionally builds 11 km depth to satisfy its two-depth minimum.

The small frequency bands and coarse grids demonstrate computation and data interpretation. They are not numerical-convergence evidence for a research application. Consult scientific conventions before comparing backend amplitudes, tensor components or time origins.