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This module generates synthetic seismic data by simulating acoustic wave propagation through a 2D velocity model using the finite-difference method. Starting from a point source described by a Ricker wavelet, the module numerically solves the acoustic wave equation on a grid derived from the input velocity model, recording the pressure field at each receiver position over time. The result is a synthetic seismic gather that mimics what would be recorded in a physical survey over the given earth model.
Use this module to create synthetic seismograms for forward modelling studies, to validate velocity models, or to generate benchmark data for testing processing workflows. The module uses a second-order finite-difference stencil with Clayton-Engquist absorbing boundary conditions applied at all four edges of the model to suppress artificial reflections from the model boundaries. A wavefield snapshot display is updated periodically during computation so you can visually monitor wave propagation in real time.
Note: This module is deprecated. For more advanced 2D and 3D finite-difference modelling with additional options such as exploding-reflector and post-stack RTM modes, use the Finite difference 2D/3D modelling module instead.
Connect the sorted trace-header index for your seismic dataset. This index defines the source-receiver geometry used in the simulation: each unique source position in the index becomes one modelled shot, and the receiver positions for that shot determine where the synthetic wavefield is sampled. The dataset must be sorted by source (shot) gather. The module processes one source at a time, iterating over all sources found in the index.
Connect the 2D interval velocity model to be used for wave propagation. The velocity model is supplied as a gather where columns represent lateral positions and rows represent depth samples. Velocity values must be in m/s. The model spatial sampling (lateral step and depth step) is read directly from the gather geometry; if the lateral and depth sampling intervals differ, the module automatically resamples the model onto a uniform grid using the finer of the two intervals to ensure numerical stability. The velocity model extent determines the area of the simulation — the synthetic receivers and sources must fall within this extent.
The total duration of the modelled seismic record, in seconds. The simulation advances the wavefield from time zero up to this value, and the output trace length equals this duration. Default: 3 s. Set this value to be at least as long as the two-way travel time from the surface to the deepest reflector of interest. Longer times increase computation time proportionally, since the finite-difference time-stepping loop runs until this limit is reached.
The time sampling interval of the output synthetic traces, in seconds. Default: 0.002 s (2 ms). This controls the temporal resolution of the saved synthetic seismogram. Note that the internal finite-difference time step used for numerical stability is computed automatically from the velocity model (it is typically much smaller than the output sample interval); the output is sub-sampled from the internal wavefield at the interval specified here. Choose a value consistent with the Nyquist criterion for the maximum frequency you intend to model — for example, a maximum frequency of 50 Hz requires a sample interval no coarser than 0.010 s.
The maximum frequency content of the modelled wavefield, in Hz. Default: 50 Hz. The source wavelet is a Ricker wavelet whose peak (dominant) frequency is set to half the value entered here — so a maximum frequency of 50 Hz produces a Ricker wavelet with a 25 Hz peak frequency. Higher values produce a broader-band, shorter-duration source pulse that resolves finer details in the model, but also require a finer spatial grid (shorter model grid step) and a smaller internal time step to remain numerically stable, significantly increasing computation time and memory use. Choose the maximum frequency to match the bandwidth of your real data.
The path and filename for the output SEG-Y file that will contain all synthetic shot gathers produced by the simulation. Each source position generates one shot gather, and the results are written sequentially (appended) to this single file as the computation progresses. Specify a full file path with a .sgy or .segy extension. The file is created fresh at the start of execution; if a file already exists at that path it will be overwritten.
The output synthetic seismic gather for the most recently processed source position. Each trace in the gather corresponds to one receiver, and the trace length equals the Max time of calculation divided by the Sample interval. Receiver amplitudes represent the pressure wavefield recorded at the surface after propagating through the velocity model. This output can be connected to downstream processing modules for further analysis or display. The complete multi-shot result is also written to the SEG-Y file specified in OutputFileName.
During computation, the module periodically updates a 2D wavefield snapshot displayed in the vista panel. The snapshot shows the instantaneous pressure field across the entire model area at fixed time intervals (every 0.05 s), allowing you to visually monitor how the wavefront expands from the source, interacts with velocity contrasts, and is absorbed at the model boundaries. This display is for quality-control purposes only and does not affect the output data.