A particular island has 100 inhabitants. None of them know their own eye colour. They are all perfect logicians. Every night at midnight, a ferry stops on the island, and every islander who has figured out their own eye colour leaves. Every islander knows the eye colour of every other islander, and knows exactly who is still on the island, but they don't otherwise communicate. All the islanders know all the rules in this paragraph.
As it happens, every islander has blue eyes.
On the summer solstice, at noon, it becomes common knowledge among the islanders that at least one person on the island has blue eyes.
So far this sounds almost exactly like the classic "hardest logic puzzle in the world", and we might assume that nobody will leave the island until the 100th visit of the ferry, at which point all islanders leave.
But at noon exactly 50 days after the summer solstice, the island volcano erupts, killing 50 of the islanders.
Assuming no further unforeseen events, do the remaining islanders make it off the island, and if so, when?