📈 Inertial Seismograph: Damped Pendulum Response and Drum Record (2D)

Side view of a heavy mass on a spring and dashpot inside a frame that moves with the ground, writing a trace on a scrolling drum beside the ground motion itself. Set the natural period, damping ratio and the ground amplitude and period, or play a synthetic earthquake with P, S and surface waves, and see the gain, phase lag, decrement and resonance peak. A time-stepped integration is checked against the formulas, with four in-page numerical checks.

2D · HTML5 Canvas 2D · 60 FPS target · runs fully client-side, no install