The video below is a small-scale demonstration of something almost impossibly large: how a megathrust earthquake can suddenly turn the ocean into a weapon. The basic mechanics are frighteningly simple. Two tectonic plates become locked while one is forced beneath the other. Stress builds for decades or centuries until the fault finally ruptures. When the seafloor abruptly jumps upward or drops, it displaces the column of seawater above it, sending tsunami waves racing outward. Take a look at a simulation of such an event linked here and below. View this post on Instagram One of the most dangerous places on Earth for that scenario sits just offshore of the Pacific Northwest. The Cascadia Subduction Zone stretches roughly 600 miles from Northern California to British Columbia, where the Juan de Fuca Plate is being driven beneath North America. A full rupture could produce an earthquake around magnitude 9.…