São Miguel Island in the Azores has a long volcanic history, with eruptions recorded from early on in the Portuguese occupation. Three tectonic plates meet near the island, and provide its volatile physical geography.

Islanders might have grown used to earthquakes, but even by São Miguel’s standards, 1811 was a bad year. Tremors hit the island from January until June. On 12 June, an underwater eruption created a new island in the sea about a mile and a half from São Miguel.

Captain Tillard, commanding the Royal Navy sloop Sabrina, saw smoke from the eruption. Assuming a naval battle was under way, Tillard set course for the eruption.

With no battle to be found, Tillard instead set out to explore the volcano. ‘To give you an adequate idea of the scene by description is far beyond my powers; but for your satisfaction I shall attempt it,’ he said when he told his story to the Royal Society the following year.

When Tillard landed on the new island he found black cinders, ash and stones shooting up to form a spire. White smoke floated about  in ‘the most fanciful manner imaginable’. Lightning completed the scene on the four-day old island, which Tillard judged to be about a mile wide. In three hours he saw the island grow some 60 feet in height.

HMS Sabrina with the new island as drawn by Lt. John William Miles, 19 June 1811

Aftershocks, along with a noise ‘like the continued firing of cannon and musquetry intermixed’, kept Tillard alert. And rightly so. While eating with his companions, an aftershock brought down a cliff face some 150 feet from the party.

‘So soon as our first consternation had a little subsided, we removed about ten or a dozen yards further from the edge of our cliff, and finished our dinner,’ said Tillard.

Tillard made one further visit to the island. This time he  found a stream that was boiling to the touch. The party planted a flag with a message in a bottle left at the base describing how the island was formed . Tillard named the island Sabrina.

What could have been an awkward (if minor) diplomatic wrangle with Portugal over Britain’s latest possession was resolved a few months later when Sabrina collapsed back into the sea.