November 18, 1867 Tsunami: Virgin Islands, US Territories

Several phenomena occurred during this event, including a double tectonic tsunami generated by violent back-to-back earthquakes [Ms=7.5] that originated 15 to 20 kilometers southwest of St. Thomas, along the north scarp of the Anegada Trough. Characterized by initial vertical oscillations, probably due to a massive down-drop of the fault blocks, the two tremendous shocks separated by an interval of 10 to 15 minutes launched immense tsunamis that propagated in all directions, the second larger than the first. The leading trough caused the ocean to recede from shores on all sides of the seismic convulsion. Produced as well, were the landslide tsunami at Guadeloupe and possible volcanic activity at St. Thomas and at Grenada. The most momentous tsunami known to have affected the U.S. Virgin Islands, the Danish West Indies at the time, it was also significant because of its impact on much of the rest of the Caribbean. Waves were reported from Jamaica to Grenada.

The 3 ships-of-war, the Susquehanna, De Soto, and Monongahela, comprised a squadron of naval vessels that brought U.S. officials to the Danish West Indies to consummate the purchase of the islands from Denmark. The negotiations failed, due not only to the 5 deaths and damage to 2 of the 3 warships sent there, but also to growing doubt about the advisability of purchasing islands prone to such havoc as the devastations by the hurricane, the earthquake, the tsunami, and the yellow fever epidemic that followed. (A cholera epidemic rampaged the island exactly one year before.) Yellow fever carried off Rear Admiral Palmer, Commander of the U.S. fleet, 3 weeks later.

"Brete Harte added his parody about the situation as a poem about the 'demise' of St. Thomas entitled: 'Saint Thomas, A Geographical Survey,' beginning:

Very fair and full of promise

Lay the island of St. Thomas

...

So the Mountains shook and thundered,

And the Hurricane came sweeping,

And the people stared and wondered,

As the Sea came on them leaping:

Each, according to its promise,

Made things lively at St. Thomas.

Till one morn, when Mr. Seward

Cast his weather eye to leeward,

There was not an inch of dry land

Left to mark his recent island.

Not a flagstaff or a sentry,

Not a wharf or port of entry,-

Only-to cut matters shorter-

Just a patch of muddy water

In the open ocean lying,

And a gull above it flying.

(above from Reference #1492)

Reid and Taber report: "A great sea wave was started by the first shock, and a second larger one by the second shock some ten minutes laters; other waves followed but were relatively unimportant. They traveled in all directions; rapidly toward St. Croix and Viequez and the south coast of Porto Rico on account of the deep water, losing energy slowly, and becoming small toward the western part of the south coast; rapidly towards the east, where they fell upon the northern Leeward Islands; rapidly all around the western end of St. Croix and across the deep water of the eastern Caribbean Sea to Guadeloupe and the islands south of it, as far as Grenada, nearly 800 kilometers from the origin" (Reference #360).

Note: Select runups attributed to this tsunami event (including the max runup at Little Saba, USVI) are due to local tsunamis generated by either earthquake-generated landslides and, possibly, volcanic activity. However, the cause code assigned to this tsunami event is 1 (earthquake) due to the earthquake being the main source of tsunami generation