Geography 2152F/G Lecture 3: Geo of Hazards - Lecture 3
27 Oct 2018
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Document Summary
They are produced by the sudden displacement of water. Events capable of triggering tsunamis: earthquakes that cause uplift of the seafloor, landslides, volcano flank collapse, underwater volcanic eruptions, meteorites. Earthquakes can cause tsunamis in two ways: by displacement of the seafloor, by triggering a landslide that enters water. 16,000: generally, an earthquake must be of at least m 7. 5 in order to trigger a tsunami. Tsunamis develop in a 4 stage process. Displacement of the seafloor sets waves in motion that transmit energy upward and outward. When the waves reach the surface of the water, they spread outward. The waves move rapidly across the open ocean (they can reach speeds of over 500 km/h). The spacing of the wave crests is very large (it can be more than 100 km). The height (amplitude) of the waves is often small (less than 1 m). Passengers on ships in the ocean rarely even notice tsunamis passing beneath them.
