The Caroline Islands are volcanic in origin, but I'm unaware of any current volcanic activity. Do you have a link? And why would this be a factor in the grounding?
--Boot Hill
Underwater volcanic activity can raise sea beds, and make charts inaccurate.
I'm looking, but cant seem to find anything recent in the yap trench area.
"The Caroline Islands are volcanic in origin, but I'm unaware of any current volcanic activity"
That's because there isn't any. I was in the Carolines not long ago- not an active volcano to be found.
From NASA:
"Studies of the Eastern Caroline Islands in the western Pacific indicate that the islands were formed by a hot spot located near the paleoequator between 1 and 11 Ma. The islands show a linear progression by mean ages from 1 Ma in the east (Kusaie) to 11 Ma in the west (Truk). The results of volumetric measurements and geochemical studies suggest that the hot spot source is waning and perhaps was slowly dying during the time Truk, Ponape, and Kusaie were being formed".