The history of Eruptions on Mount Teide: Teide last erupted in 1909 from the El Chinyero vent, on the Santiago Ridge. Historical volcanic activity on the island is associated with vents on the Santiago or northwest rift (Boca Cangrejo in 1492, Montañas Negras in 1706, Narices del Teide or Chahorra in 1798 and El Chinyero in 1909) and the Cordillera Dorsal or northeast rift (Fasnia in 1704, Siete Fuentes and Arafo in 1705). The 1706 Montañas Negras eruption destroyed the town and principal port of Garachico, as well as several smaller villages.
Historical activity associated with the Teide and Pico Viejo stratovolcanoes occurred in 1798 from the Narices del Teide on the western flank of Pico Viejo. Eruptive material from Pico Viejo, Montaña Teide and Montaña Blanca partially fills the Las Cañadas caldera. The last explosive eruption involving the central volcanic centre was from Montaña Blanca around 2000 years ago. The last eruption within the Las Cañadas caldera occurred in 1798 from the Narices del Teide or Chahorra (Teide’s Nostrils) on the western flank of Pico Viejo. The eruption was predominantly strombolian in style and most of the lava was ʻAʻā. This lava is visible beside the Vilaflor–Chio road.
Christopher Columbus reported seeing “a great fire in the Orotava Valley” as he sailed past Tenerife on his voyage to discover the New World in 1492. This was interpreted as indicating that he had witnessed an eruption there. Radiometric dating of possible lavas indicates that in 1492 no eruption occurred in the Orotava Valley, but one did occur from the Boca Cangrejo vent.
The last summit eruption from Teide occurred about the year 850 CE, and this eruption produced the “Lavas Negras” or “Black Lavas” that cover much of the flanks of the volcano.
About 150,000 years ago, a much larger explosive eruption occurred, probably of Volcanic Explosivity Index 5. It created the Las Cañadas caldera, a large caldera at about 2,000 m above sea level, around 16 km (9.9 mi) from east to west and 9 km (5.6 mi) from north to south. At Guajara, on the south side of the structure, the internal walls rise as almost sheer cliffs from 2,100 to 2,715 m (6,890 to 8,907 ft). The 3,718 m (12,198 ft) summit of Teide itself, and its sister stratovolcano Pico Viejo (3,134 m (10,282 ft)), are both situated in the northern half of the caldera and are derived from eruptions later than this prehistoric explosion.
Spain’s highest mountain – Mount Teide – is closer 7500m tall when measured from the seafloor. You can also see a live webcam image from Mount Teide here.
Source: Wikipedia