Watch the wave size dramatically increase when entering sediments! Waves become 3-4x larger due to impedance contrast. The slower velocity concentrates energy, creating much stronger ground motion.
See the wave path bend sharply toward vertical when hitting the boundary! Angles can change by 30-50 degrees. This refraction follows Snell's law and focuses seismic energy upward.
Energy bounces between layers, creating prolonged shaking. Trapped waves (yellow) show how sedimentary basins can shake much longer than bedrock sites during earthquakes.