Which describes the waves formed by tsunamis
Tsunamis are formed by large undersea earthquakes or volcanic eruptions, and the waves they create are typically referred to as long-period seismic sea waves. These waves have extremely long wavelengths and travel at high speeds across the ocean, reaching heights of up to 30 meters (100 feet) when they approach the coastline. Unlike most ocean waves, tsunamis have a lower wave height-to-wavelength ratio and can travel across entire ocean basins without significant loss of energy. As they approach the coastline, the tsunami waves may experience shoaling, causing them to slow down and increase in height, resulting in the destructive impact that is commonly associated with tsunamis.
Tsunamis are typically characterized by long-period waves that can travel across entire ocean basins. These waves are often referred to as seismic sea waves or harbor waves. The following steps describe the formation of waves by tsunamis:
1. Triggering Event: Tsunamis are usually generated by large undersea earthquakes, volcanic eruptions, or submarine landslides. These events displace a significant amount of water, resulting in the formation of initial waves.
2. Energy Transfer: The energy released by the triggering event propagates through the water, causing the initial waves to spread out in a radial pattern.
3. Deep Water Waves: In deep ocean waters, tsunamis are characterized by long wavelengths (the distance between wave crests) and low wave heights. These waves can travel at high speeds, often exceeding 500 miles per hour (800 kilometers per hour).
4. Wave Height Amplification: As the tsunami approaches shallower coastal areas or encounters variations in ocean floor topography, including underwater ridges and trenches, the wave energy can become compressed and the wave height increases.
5. Drawback Effect: As the leading edge of the tsunami approaches the shoreline, it can cause a temporary retreat of water, often referred to as a drawback effect. This can expose the seabed and can be a warning sign of an incoming tsunami.
6. Inland Inundation: When the tsunami reaches the coastline, it can cause devastating flooding and widespread destruction. The wave energy can inundate low-lying coastal areas, reach far inland along river valleys, and have the potential to travel hundreds of miles (kilometers) from its source.
It is important to note that tsunamis are different from wind-generated waves. Unlike wind waves, tsunamis have much longer wavelengths, very low wave heights in deep water, and can carry a tremendous amount of energy as they propagate across the ocean.