A tsunami has hit Tonga's largest island, Tongatapu, after an underwater volcano in the South Pacific erupted. | CNN

Imagine a tsunami so wide and epic it engulfs an entire country in seconds 🌊 A single wall of water racing across the land, horizon to horizon — dramatic, cinematic, and terrifying. This won’t happen though, because scientifically: • Tsunamis don’t behave like fast-moving flood walls across land; they are long, low waves in deep ocean that only rise near coastlines. • Their speed drops drastically once they hit shallow water and land due to friction and terrain. • Energy spreads out as waves tr