Tsunamis

Wave Properties and Behavior

Wave Height to Wavelength Ratio

• A critical ratio for understanding wave behavior is the ratio of wave height to wavelength.

• The specific ratio at which a wave will start to crash is one to seven (1:7).

  • Definition: This means that for every unit of wave height, there are seven units of wavelength.

  • Example: If a wave has a height of 1 meter, its wavelength would be 7 meters.

Wave Crashing

• Once a wave reaches the critical steepness defined by this ratio, it will begin to crash.

  • Implications: This crashing occurs when the wave becomes unstable due to its height relative to its length.

• Location Context: If observing from the shoreline, it is evident that the wave has reached this critical steepness and is poised to fall over onto itself.

Changes in Wave Dynamics as it Approaches the Shore

• As a wave travels towards the shoreline, it experiences several significant changes:

  1. Slowdown of the Wave:

  • The wave gradually slows down as it feels the bottom, interacting with the ocean floor.

  1. Increase in Wave Height:

  • As the wave slows down, its height increases, making it steeper.

  1. Decrease in Wavelength:

  • Simultaneously, the wavelength of the wave decreases, leading to a steeper slope which contributes to the possibility of crashing.

Summary of Wave Behavior

• Understanding the height-to-wavelength ratio and the dynamic changes occurring as waves approach the shore is crucial for predicting wave behavior and ensuring safety in coastal activities. The transition from a stable to a crashing wave is marked by the critical ratio of 1:7, followed by changes in height and wavelength as the wave interacts with the ocean floor.