Volcanoes, earthquakes and tidal waves

Conrad Martens' contemporary sketch of the volcano of Osorno, seen from Chiloé. CUL MS.Add. 7984. f. 23

Travelling north along the coast of Chile, Darwin and FitzRoy were confronted with a series of violent natural events that they were perfectly placed to study. They witnessed the eruption of Mount Osorno, and then a month later a large section of the west coast was shaken by an earthquake, and in Concepción, a tidal wave engulfed the town demolishing most of the buildings. It was not just the large-scale devastation wreaked in the towns and villages that made an impression on them; they also noticed the small but measurable, and apparently permanent, effects on the land surface itself. FitzRoy repeated his survey of 1834 and demonstrated that the surface of the land at Concepción had risen in altitude. Travelling inland, Darwin concluded that all these separate surface events could be explained by postulating shock waves from a single subterranean event.