A tsunami that sunk an island?

[Naito-desu]

Basically an island of undescript size gets sunken by a tsunami, energy for this?

 

[The_Axiom_of_Virgo]

I'm no means knowledgeable about calculations but without further context it takes quite a few assumptions no?

*You'll have to assume the size of the island so we have to use a small island as the baseline.

*The composition of the island. Does it have mountains, forests, buildings, etc? I guess a small rocky island?

*The volume of water it would take to sink a small rocky island via a tsunami.

*Also using different timeframes for the tsunami.

Overall it sounds like a classic tier 7 feat to me but without further context it's hard to get a solid rating imo.

 

[Naito-desu]

The feat is basically contextless save for it containing a city purportedly made of gold

 

[Naito-desu]

As the last of the Mage-Priests left, a mighty wall of water arose to block out the very sun. The waters that had receded now returned as a tsunami many hundreds of yards high. The seas broke not only upon Chupayotl, but the greater part of its population too. The waters carried many miles into the jungle, flattening a vast area before its force was spent. As the waters swept back to the ocean, the sea level finally equalised and Chupayotl was gone, swept into the ocean along with thousands of its former occupants. Tragically, the Mage-Priests of Chupayotl fell too that day, dashed against the ruins of their own temple-city.

 

[The_Axiom_of_Virgo]

Still sounds tier 7 to me but the tsunami being hundreds of yards high metric system supremacy and going through miles of forest land might potentially bump it into tier 6 (especially since the time frame seems pretty short) but that's my two cents on the matter.