Seafloor displacement, wave speed, and coastal shoaling
Click water to set epicenter · Hover for local wave height
A tsunami is generated by sudden vertical seafloor displacement (earthquake, landslide). In deep ocean, speed ≈ √(g·d) — up to 800+ km/h with wavelengths of 100-200 km but only ~1 m height. As the wave enters shallow water, it slows but amplitude increases dramatically (shoaling). The wave height can grow 10-30× near shore. Warning time depends on distance from epicenter.