Just note here so that people unfamiliar of tsunamis won't get misconception. 50cm of tsunami is enough to wash people away. It's totally different from 50cm-high wave[1]. 1m of tsunami is deadly if you got swallowed. 3m can easily sweep two-story houses.
[1] This illustration depicts the difference: https://twitter.com/_KE_N_/status/295134747603107840/photo/1 Calculate the inertia of the water. Also mind the actual tsunami carries lots of debris so you can't easily swim in it.