Explained: Why a Russian earthquake triggered tsunami alerts in Hawaii, Japan, and the US West Coast

Such quakes happen along subduction zones—where one tectonic plate dives beneath another—causing the ocean floor to jolt violently. That displacement sends out shockwaves in the form of tsunami waves. These waves travel at speeds of up to 800 km/h and fan out in all directions, much like ripples from a stone dropped in a pond.