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11.8: What is a Tidal Wave?

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    10327
    • Contributed by Miracosta Oceanography 101
    • Sourced from Miracosta)

    What is a Tidal Wave?

    Tidal wave is a term often confused with the term tsunami. They are different.
    Tsunamis are seismic sea wave formed by rapid displacement of the seafloor, such as by earthquakes, volcanic explosions, landslides, etc.). Tsunamis are not related to tides. Tsunamis are generally unpredictable, especially close to the source of the disturbance, with only minutes to hours to warn large coastal populations.

    A tidal wave is a large wave associated with a tidal bore. A tidal bore is a surging flow of a large about of water moving with the incoming tide that funnels a large amount of water into a river mouth or a narrow bay (Figure 11.16). Tidal bore can produces sizable waves that move inland along rivers and estuaries (they are surges of water that can behave like a tsunami). Tidal bore characteristics are often predictable, but can be influenced by storm surges and high sea waves causing potentially hazardous conditions.

    Tidal bore near Truro, Nova Scotia Sea cliff at Del Mar Dog Beach
    Figure 11.16. A tidal bore moving up a tidal estuary near Truro, Nova Scotia on the Bay of Fundy. A tidal bore is associated with the surge of an incoming ebb tide. Figure 11.17. High tide combined with storm waves can cause intense erosion at the base of sea cliffs, such as illustrated here at the Del Mar Dog Beach, CA.

    Check out these tidal bore videos:
    Tidal bore surfing on the Bono waves, Kampar River, Indonesia (YouTube video)
    Tidal bores surge in Qiantang River(YouTube video)
    Tidal Bore Surfing Seven Ghosts in Indonesia (YouTube video)