Seismic Wave Propagation Simulator: Cross-Section (2D)

This 2D companion trades the orbiting 3D globe for a flat cross-section built to make the wave physics legible: a control panel sets earthquake magnitude, focal depth, the epicenter's position around the ring and a time-scale multiplier, and pressing Trigger earthquake expands P and S wavefronts outward from the hypocenter while a surface wave spreads both ways along the crust. The wavefront radius is computed the same way as the 3D version — integrating through four PREM-like layers (inner core, outer core, mantle, crust), each with its own P and S velocity — so the model reproduces the real P-wave velocity jump at the core boundary and the S-wave shadow zone caused by the liquid outer core. Eight fixed ring stations register P, S and surface arrival times, and a seismograph panel plots a synthetic waveform for whichever station is selected.