There is no volcanic ridge or feature known as "Kyunshu-Palau-Ridge." It's possible there's a misunderstanding or a typo in the name.

To help me understand your query better, please provide:

* The correct spelling of the name.

* The specific geographic location.

* Any other details you may have about the volcanic feature.

Once I have the correct information, I can help you find out when the last eruption occurred.