Which term is specifically associated with extremely long wavelengths generated by sudden sea floor displacement, often in open ocean?

• A. Wave
• B. Wave Crest
• C. Tsunami
• D. Wave Height

Answer: (C)

This term describes extremely long-wavelength ocean waves generated by a sudden movement of the sea floor, often far from shore in the open ocean. That sudden displacement—caused by events like submarine earthquakes, landslides, or volcanic eruptions—produces waves with wavelengths hundreds of kilometers long. In deep water these waves travel very fast and have only small heights, so they can go unnoticed until they reach shallower areas where their speed drops and their height increases dramatically, leading to the large surge associated with Tsunamis.

Other options don’t fit as well because a general wave is simply a surface disturbance often driven by wind with much shorter wavelengths; the term for a wave crest is just the top part of any wave, and wave height is a measurement of a wave’s vertical extent, not the phenomenon itself.