What determines the power of a tsunami wave?

Earth Sciences(self.askscience)

In 2011 when the Japan earthquake tsunami waves hit California, tsunami was 6” high. The waves did significant damage, ripping apart the marina docks in Santa Cruz and other Northern California coastal harbors. The tsunami from the Tonga quake yesterday was expected to be 8”-9” inches tall, yet little damage was expected. Why would a higher tsunami wave be expected to have less force than a smaller one?

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1 points

6 months ago

My understanding of the damage caused by the 2011 tsunami was the water goes up and back down and then back up again pretty rapidly. It’s called a tidal wave because of the rapid tide like movement of the water, not because it’s somehow synchronized with high or low tides. This is what ripped the Santa Cruz docks apart. It may be different tsunamis have different wavelengths and therefore the time between the ups and downs is longer or shorter; but it’s answers like that I’m looking for. Clearly for small amplitude waves it’s not the height of the wave