Geography 2152F/G Lecture 3: Lecture 3 Notes
31 May 2016
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Events capable of triggering tsunamis: earthquakes that cause uplift of seafloor, landslides, volcanic flank collapse, underwater volcanic eruptions, meteorites. Earthquakes can cause tsunamis in 2 ways: displacement of seafloor or triggering a landslide that enters water. Generally the earthquake must be at least m7. 5 to trigger a tsunami. Tsunamis develop in a 4 stage process: Stage 1: displacement of seafloor sets waves in motion that transmit energy upward and outward, when waves reach the surface of the water they spread outward. Stage 3: as tsunami approaches land, the water depth decreases, the results in the water. Piling up" causes a decrease in wave speed and spacing of the waves and an increase in wave amplitude (height) Stage 4: tsunami impacts land, waves can reach heights of dozens of metres, wave speed can be up to 50km/h: during some tsunamis the water first recedes from the shore and exposes the seafloor.
