... like I'm 5 years old
A tsunami is a series of massive waves that occur in the ocean. They are usually caused by events that disrupt the ocean, like earthquakes, volcanic eruptions, landslides, or meteor impacts. Imagine if you're in a bathtub and you suddenly stand up. The water around you will move, creating waves. This is similar to what happens in the ocean when there's an earthquake or volcanic eruption. The earth's crust shifts, displacing water and creating waves. These waves travel across the ocean, increasing in size as they approach land, causing destruction when they reach the shore.
To understand tsunamis, think of a pebble being thrown into a pond. The pebble disrupts the water, creating ripples that spread out from the point of impact. In the ocean, an earthquake is like this pebble, causing ripples that turn into massive waves, which we call tsunamis.
... like I'm in College
Tsunamis are not typical waves; they’re energy waves, mostly caused by geological disturbances beneath the sea. The most common cause is subduction zone earthquakes. A subduction zone is where two of the earth's tectonic plates meet and one slides under the other. When these plates shift suddenly, it displaces large volumes of water, producing waves that move away from the epicenter.
As the waves travel across deep oceanic waters, they move at high speeds often unnoticed. However, as they approach shallower coastal waters, wave speed decreases but its height increases dramatically, leading to the towering walls of water associated with tsunamis.
Imagine a flat Lego baseplate as the ocean floor and, using different colored bricks, build a raised section to represent tectonic plates. Now, create tension by pushing these Lego 'plates' together. When you release the pressure suddenly, the Lego bricks shift, imitating an undersea earthquake.
Next, place flat blue Lego tiles to represent the ocean water. When the 'earthquake' occurs, it would disturb these tiles, sending them moving away from the earthquake's location, much like a tsunami wave.
To show the wave approaching land, build a gradual slope leading up to a flat surface to represent the shoreline. As the wave (blue tiles) moves towards the shore, they would cluster and pile up, representing the wave's increase in height as it reaches shallow waters and eventually hits land, much like a real tsunami would.
... like I'm an expert
From a geophysical perspective, the generation of a tsunami involves a sequence of events. The subduction of an oceanic plate under a continental plate builds up significant pressure over time. When this pressure is released, it triggers an undersea earthquake.
The seismic energy from the earthquake is transferred to the overlying water column, initiating the tsunami wave train. The wave parameters (height, speed, and wavelength) are influenced by factors such as the magnitude and depth of the earthquake, and the water depth over the epicenter.
As the tsunami waves approach the coastline, wave shoaling occurs—a reduction in wave speed due to decreasing water depth. This causes wave amplification, which results in the dramatic increase in wave height, leading to catastrophic coastal impacts.