Geography 2152F/G Lecture 3: L3
16 Mar 2017
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Document Summary
Tsunamis (cid:498)harbour wave(cid:499: produced by sudden displacement of water, events capable of triggering tsunamis, earthquakes cause uplift of seafloor, landslides, volcano flank collapse, underwater volcanic eruptions, meteorites. Earthquake cause tsunamis in 2 ways: displacement of seafloor, triggering landslide that enters water. Generally, earthquake must be at least m (magnitude) 7. 5 in order to trigger a tsunami. Stage 1: displacement of seafloor sets waves in motion that transmit energy upward and outward: waves reach surface of water, spread outward. Stage 3: tsunami approaches land, water depth decreases due to sea levels rising: result in water (cid:494)piling up(cid:495) and causes these effects, decrease in wave speed, decrease in spacing of waves, increase in wave amplitude. Stage 4: as tsunami impacts land, waves can reach heights of dozens of metres: wave speed can be up to 50km/h making them impossible to outrun, during some tsunami, water first recedes from shore and exposes seafloor. In atlantic, no subduction zones because plates are diverging.
