The archipelagos of Madeira and the Azores are scattered within the Atlantic Ocean: the Azores straddling the Mid-Atlantic Ridge on a tectonic triple junction, and Madeira along a range formed by in-plate hotspot geology. Geologically, these islands were formed by volcanic and seismic events. The last terrestrial volcanic eruption occurred in 1957-58 (Capelinhos) and minor earthquakes occur sporadically, usually of low intensity.