Sonic tectonic baseline shifts
Warp the heavens’ ocean floor
Tipping the teacup, a sea of ideas
Spilling onto a reticent shore...

A Tsunami starts in mid-ocean with a long, vast, fast-moving wave caused by a shifting of the ocean floor (see "tectonic plates"). Initially only half the height of a normal wave, it grows much taller as it approaches land (its length compressed by the rising ocean floor), ultimately reaching monstrous heights as it hits shore.

"Tsunamis have a small amplitude (wave height) offshore, and a very long wavelength (often hundreds of kilometers long) which is why they generally pass unnoticed at sea, forming only a slight swell usually about 300 mm above the normal sea surface. They grow in height when they reach shallower water

While everyday wind waves have a wavelength (from crest to crest) of about 100 metres (330 ft) and a height of roughly 2 metres (6.6 ft), a tsunami in the deep ocean has a wavelength of about 200 kilometres (120 mi). This wave travels at well over 800 kilometres per hour (500 mph), but due to the enormous wavelength the wave oscillation at any given point takes 20 or 30 minutes to complete a cycle and has an amplitude of only about 1 metre (3.3 ft). This makes tsunamis difficult to detect over deep water. Their passage usually goes unnoticed by ships.

As the tsunami approaches the coast and the waters become shallow, the wave is compressed due to wave shoaling and its forward travel slows below 80 kilometres per hour (50 mph). Its wavelength diminishes to less than 20 kilometres (12 mi) and its amplitude grows enormously, producing a distinctly visible wave. Since the wave still has a wavelength on the order of several km (a few miles), the tsunami may take minutes to ramp up to full height, with victims seeing a massive deluge of rising ocean rather than a cataclysmic wall of water. Open bays and coastlines adjacent to very deep water may shape the tsunami further into a step-like wave with a steep breaking front.

If the first part of a tsunami to reach land is a trough (draw back) rather than a crest of the wave, the water along the shoreline may recede dramatically, exposing areas that are normally always submerged. This can serve as an advance warning of the approaching tsunami which will rush in faster than it is possible to run. If a person is in a coastal area where the sea suddenly draws back (many survivors report an accompanying sucking sound), their only real chance of survival is to run for high ground or seek the high floors of high rise buildings."

This NASA image of Aurora Borealis resembles a giant breaking wave of light, evoking a different kind of Tsunami that brings vision, not catastrophe, as it washes over the "reticent shore" of our waking minds.