Whose discovery explained the cause of tsunami generation by seafloor movement?

Tsunamis are primarily generated when large sections of the seafloor move abruptly, usually during major undersea earthquakes. Early 20th-century geophysicists including Harold Jeffreys helped develop the physics needed to understand how that displacement sets ocean water in motion. Later research tied tsunami waves to thrust-fault earthquakes in subduction zones. This scientific understanding made it possible to design warning systems based on earthquake location, depth, and magnitude. It is one of the clearest examples of science directly saving lives.