Citation: http://edition.cnn.com/2013/09/06/world/biggest-volcano/index.html?c=world
If it is a seismic center, we have to worry about tsunami. Especially this volcano is not far from the seismic center which caused Earthquake of East Japan in 2011. So, the similar damage may happen.
As far as the article says, we can't judge whether the volcano is the extinct volcano or the dormant volcano.
If the volcano were to erupt, what would happen?