Why developing countries are least able to cope with the devastating effects of tsunamis​

Because they have the most to lose, imagine it like you have 10 towers and all collapsed from a tsunami. And the village next to you also collapses. The ten towers lost way more money and people in it then the villages

In short answer, The developed country just simply has a lot more to lose then the lesser developed one.

When two tectonic plates collide and one or both push upwards they also push up the crust,a mountain will for so that will be your answer. hoped this