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Geography and Geology

The islands of the Azores are located along the mid-Atlantic ridge system, atop an active triple junction between three large tectonic plates: the North American Plate, the Eurasian Plate and the African Plate. The two westernmost Azorean islands (Flores and Corvo) actually lie on the North American plate. All of the islands have volcanic origins, although one, Santa Maria, also has some reef contribution and an abundance of sediments where marine fossils have been discovered.

Fig 3_Volcanism associated with the formation of the islands arises from the fact that the Azores Triple Junction involves rifting, a process whereby the crust is spreading along three ridge legs radiating out from the triple junction. The volcanism is also related to the Azores hotspot. Geologically, the Azores comprise a 20–36-million-year old volcanic plateau; the oldest rocks (composing Santa Maria Island) emerged 8.120 million years ago, whereas the youngest (forming Pico Island) are about 250,000 years old.

Fig 4_Due to their volcanic origin, the islands are by nature rugged, with high peaks contrasting with calderas (large depressions resulting from the collapse of the centre of volcanic systems) that host interesting lagoon systems. As a result of several recent historical lava flows, there is a great concentration of lava tube caves and pits in the Azores. A total of 250 underground cavities, including lava tubes, volcanic pits, pit-caves, and sea-erosion caves, are known to exist in the Azores, creating many kilometres of cave passages, extraordinary geological formations, and unique fauna adapted to caves. The relatively recent volcanism of the Azores results in the occurrence of numerous associated phenomena, such as thermal springs, geisers and hot springs, as well as high seismic activity.
Fig 5 (coming soon)
The last volcano to erupt in the archipelago was the Capelinhos Volcano in 1957, in the western part of Faial Island, increasing the size of the island by 2.4 km, but it's estimated that the great part of it will be washed away in next 20 years.