Just for my own records

[womzilla]

The worst geological disaster awaiting the United States is the collapse of the Cumbre Vieja Volcano on La Palma, Canary Islands.

If the Cumbre Vieja were to collapse as one single block it would create a giant mega-tsunami with an initial wave height of 650 metres and a wavelength of 30-40 kilometres travelling westwards across the Atlantic with speeds up to 720 kilometres an hour towards America.

More details in this PDF.

Comments

[supergee.livejournal.com]

Frederik Pohl's The Boy Who Would Live Forever includes a similar disaster on the west coast after an earthquake in Hawaii.

[redbird]

You and I might be okay in this one, short term, just from the shape of the harbor, but yes.

Well, unless you think the Yellowstone Caldera is likely to let go anytime soon, which I don't.

[wild-irises.livejournal.com]

The Yellowstone Caldera wins the "worst disaster" award. And the one which can least be predicted or prevented. It'll go when it goes, and we probably won't (literally) even know what hit us.

[avram]

Sometime in the next ten thousand years!

Actually, there are also people who claim the threat is being blown out of proportion.