Guide to Geologic Hazards in Alaska

Tsunamis are sea waves produced by any large-scale, short-duration disturbance of the ocean floor. These may be caused by shallow submarine earthquakes, but also by submarine slumps, subsidence, or volcanic eruptions. Tsunamis generated thousands of miles away can travel relatively quickly and be very destructive. Tsunami warning systems can provide ample warning for these far-field tsunamis if properly implemented. Locally generated tsunamis can reach the shore within seconds of initial wave propagation. In such cases, ground shaking is the only warning people will have.