Interactive 2-D seismic reflection simulation - Created by Diego Takahashi
2.40 km × 1.40 km · 0 layers
No simulation yet
Run the simulation to record hydrophone traces.
A short field guide to the model, the maths and the buttons.
Created by Diego Takahashi.
Load a geological preset, then edit the layer stack on the right. Each layer has a lithology, thickness, P-wave velocity and density. The velocity fields are real: seawater ≈ 1500 m/s, shale ≈ 2.5 km/s, sandstone ≈ 2.9 km/s, limestone ≈ 4.5 km/s, halite ≈ 4.5 km/s and anhydrite ≈ 6.1 km/s.
Use Paint to draw salt, reefs, channels or gas pockets with any rock in the palette. The 1-D log beside the section follows the column under the pointer (or the shot when idle), so it updates as you paint. Layer labels are hidden where paint covers them. Erase restores the layer-stack model. Shot moves the source; the hydrophone spread follows it.
Set the section width and depth in the Model tab. Deeper sections (7 km or more) reach pre-salt targets; the basal layer fills any extra depth. Bigger sections create a larger grid, so they take longer to compute and use more browser memory. The panel shows the cell count and estimated run time before you apply a size.
The source is a Ricker wavelet. The engine steps the 2-D acoustic wave equation on a finite-difference grid until the requested record length is reached. A marine streamer records pressure in the water; a land spread records just below the surface.
Every impedance contrast generates a reflection. The shot gather shows offset horizontally and two-way travel time vertically. The wavefield movie shows the same wavefronts propagating through the section.
Deeper events arrive later. Hyperbolic moveout with offset is the signature of a reflection; the dashed curves are NMO predictions from the actual model column at the shot, with representative curves for painted bodies elsewhere, so new rocks are identified rather than only stack layers. A reverse-polarity event (blue) marks a decrease in impedance — a gas sand, for example.
Use AGC to balance weak deep reflections, and the noise gate, gain and clip sliders to bring out detail. Click the gather to inspect the nearest trace in the trace inspector.
Zoom either plot with the − / + control at its top right or with the mouse wheel. Drag the response to pan; hold Shift (or use the middle mouse button) and drag the model. The reset arrow fits the view again.
4th-order centred differences in space, explicit 2nd-order in time, variable density. The time step satisfies a conservative CFL condition from the fastest layer, so raising velocities automatically shortens Δt. Sponge layers absorb the sides and base; the top is a pressure-release surface, producing realistic source and receiver ghosts.
Simulation is single-threaded and chunked so the interface stays responsive. High resolution and long records cost more time. Estimated cost is shown before every run.
Light or dark: use the Light / Dark switch in the header. The seismic plots stay dark in both themes so amplitude colours retain their contrast.
A broad working reference for reflection seismology, geological structures and oil and gas exploration.