According to Wiki[1] and UC San Diego's website[2], this was actually a 650 ft tsunami. The location probably helped for the wave's height. Per the same article, it's far from the biggest ever theorized but in a good position in the biggest ever recorded.

[1] https://en.wikipedia.org/wiki/Megatsunami

[2] https://scripps.ucsd.edu/news/climate-change-triggered-lands...