[AntiGuv]

The tsunami waves moved east and west from the earthquake, and Bangladesh was almost directly to the north so it was spared.

[Ready4Freddy]

Tsunamis radiate in a circle, of course, so there would have been waves aimed at Bangladesh. I suspect that the reason they didn't get hit was because the northern end of Sumatra angles & curves northwest, and the epicenter was tucked up close to the island several miles SE of the tip.

The Nicobar & Andaman islands to the north of Sumatra may have shielded Bangladesh as well, though they were hit hard.

The tsunami waves moved east and west from the earthquake, and Bangladesh was almost directly to the north so it was spared.