If you want to have an idea about the amount of time you have when tsunami arrives, look at this 5-minute video of tsunami attacking in Minami-Sanriku.
Warning: the video gets tough.
Not much is happening in the first two minutes or so - except for some dust above the distant beaches - even though the cameraman seems nervous from the beginning. You will understand why.
But the actual scary events eventually begin. I found it impressive how the houses remained compact yet swimming - they turned into boats. Nature is very powerful and cruel. Such events sometimes occur and they're more far-reaching than 0.008 °C of warming or cooling per year.
Thanks to Gene