The Azores: volcanic archipelago and autonomous region

Nine islands and a few islets, far out in the Atlantic, between 36 and 41 degrees north and 24 and 33 degrees west. The Azores Geopark’s application file gives the distances: 1,815 kilometres from mainland Portugal, 2,625 kilometres from Canada. The islands string out over about 600 kilometres, from Santa Maria to Corvo, for 2,324 square kilometres of land in all.

They fall into three groups, which the same file names thus: the western group (Flores and Corvo), the central group (Terceira, Graciosa, São Jorge, Pico and Faial) and the eastern group (São Miguel and Santa Maria). Sizes run from 17 square kilometres for Corvo to 745 for São Miguel. The high point, Pico mountain, rises to 2,351 metres: the highest summit in Portugal. The coasts of the nine islands total 940 kilometres, in sheer cliffs and in gentle slopes alike.

Because they sit on a triple junction. The Geopark file places the archipelago where the Eurasian, North American and African (or Nubian) lithospheric plates meet, and adds at once that the exact nature and position of these plate boundaries feed a lively scientific debate. Two structures frame the junction: the Mid-Atlantic Ridge, running north-south, separating the North American plate to the west from the Eurasian and African plates to the east, and the GLORIA fault, running west-east.

Every island is volcanic and oceanic: they emerged by the piling up of submarine volcanic products, a process thought to have begun about 36 million years ago. The oldest subaerial volcanism is dated to 8.12 million years on Santa Maria; the youngest island is Pico, formed some 300,000 years ago. The same file counts 27 main volcanic systems and more than 1,750 monogenetic volcanoes, including 9 polygenetic volcanoes and 7 basaltic fissure zones held to be active, but dormant.

This ground has not finished moving. Since discovery and settlement, in the middle of the fifteenth century, 26 eruptions have been recorded in the Azores region: 12 on land and 14 under the sea. The last two of any size were submarine, at Capelinhos, on Faial, in 1957-1958, then 8.5 kilometres northwest of the Ponta da Serreta, near Terceira, in 1998-2000. The IUGS, the international union of geological sciences, holds Capelinhos to be the first submarine eruption in the world followed and documented from end to end: it added 2.4 square kilometres to Faial, of which only a quarter is left, eaten by the sea.

Nobody knows. The Azores Geopark sums up the hesitation in one sentence: it is not known whether Diogo de Silves, in 1427, or Gonçalo Velho Cabral, in 1431, reached the archipelago first. The two oldest documents both date from 1439, and they are a map and a royal letter.

The map is that of the Majorcan Gabriel de Valsequa, which carries the nine islands and this legend: “aquestas illes foran trobades p. Diego de Silves pelot del rey de Portogall an lay MCCCCXXVII”, these islands were found by Diego de Silves, pilot of the king of Portugal, in the year 1427. The second name is hard to read: the notice of the Enciclopédia Virtual da Expansão Portuguesa speaks of a Diego de question mark and credits the reading Silves to the palaeographer Damião Peres. The same notice adds that no document or account of the time names Gonçalo Velho as the discoverer: it is Gaspar Frutuoso, at the end of the sixteenth century, who does so, from the island’s oral tradition.

The letter leaves no doubt. On 2 July 1439, at Lisbon, Afonso V makes known that his uncle the Infante Henry has had sheep released on the seven islands of the Azores and asks licence to have them settled; the king grants it. The text, printed in the Archivo dos Açores in 1878 from Afonso V’s chancery, states that the king acts with the authority of the queen his mother, his guardian. Seven islands, not nine. And sheep before settlers: the Geopark dates the release of animals to 1431-1432 and the sending of settlers to 1439.

Settlement itself took two centuries. The eastern and central groups in the fifteenth century, the western group in the sixteenth, says the Geopark. Flores and Corvo, sighted around 1452 by Diogo de Teive according to the same source, wait until 1508 for a settlement that holds, and the middle of the sixteenth century for Corvo. To the people from mainland Portugal were added Flemings, Genoese, Jews, Moors, French, English and enslaved Africans.

Because an island in mid-ocean is first of all a stopover. UNESCO describes Angra do Heroísmo, on Terceira, as an obligatory port of call for the fleets of equatorial Africa and of the East and West Indies routes, outward and homeward, from the fifteenth century until the coming of steamships in the nineteenth.

The town carries the mark of that function. Its grid plan, usually reserved for new towns, was bent to allow for the prevailing winds, and UNESCO supposes the choice was imposed by the navigators and their cartographers. Angra was raised to the rank of city on 21 August 1534 and became in the same year the seat of the archbishop of the Azores. The four-hundred-year-old fortresses of São Sebastião and São João Baptista guard the bay. The centre of Angra was inscribed on the World Heritage list in 1983, under criteria (iv) and (vi); badly damaged by the earthquake of 1980, it was repaired keeping its fifteenth and sixteenth-century street network.

Passing ships left traces in the history of the islands. In 1493 Christopher Columbus’s ships anchored at Santa Maria on the way back from the first voyage to America, the Geopark notes. Corvo, at the far west, served as a meeting point for the Portuguese armadas that came to take charge of the empire’s ships and escort them to Europe. And for two centuries English, French, Castilian and Flemish privateers made the islands a regular target: hence the fortifications.

An autonomous region of the Portuguese Republic. The political and administrative statute, in the wording given it by law no. 2/2009 of 12 January, says so in its article 1: the archipelago constitutes an autonomous region with legal personality under public law, and its political, legislative, administrative, financial and patrimonial autonomy is exercised within the framework of the Constitution and the statute. Article 2 lists the regional territory: the nine islands, named one by one, and their islets.

There is not one capital, there are three. The Legislative Assembly sits in the town of Horta, on Faial (article 25); the presidency and the regional secretariats, which make up the departments of the regional government, have their seats at Angra do Heroísmo, Horta and Ponta Delgada (article 76). The region has 19 municipalities and 156 parishes, and the European Union classes it among its outermost regions.

At the end of 2025 the regional statistical service, the SREA, puts the population at 245,328, which is 4,302 more than in 2021. The weight of the islands is nothing alike: 138,557 inhabitants on São Miguel, 434 on Corvo. More than one Azorean in two therefore lives on a single island.

Two World Heritage inscriptions and a geopark: that is what the archipelago shows of itself. The vineyard landscape of the island of Pico was inscribed in 2004, over 987 hectares with a buffer zone of 1,924 hectares, for its thousands of small rectangular enclosures, the currais, which stone walls protect from wind and spray. The vine was brought there in the fifteenth century, reached its height in the nineteenth, then declined under disease and the loss of soil. As for the Azores Geopark, it has carried the UNESCO Global Geopark label since 2015 and lists 121 geosites across the nine islands.

A vast zone of high pressure, which Météo-France calls almost permanent, settled over that part of the Atlantic. The air there is heavier, and the disturbances coming off the ocean pass to one side. The Geopark file says the same thing seen from the islands: it is the position, the orientation, the extent and the intensity of this anticyclone that govern atmospheric circulation in this region of the globe.

Météo-France explains what that means for France, and the mechanism is the same for western Europe. While the anticyclone stays over the Azores, the weather is on the cool side: Atlantic depressions travel freely over Europe. When it settles over northern or eastern Europe, it blocks those depressions, lets in winds from the east and the south, and the weather turns hot and dry. In summer, with solar energy at its greatest near the Tropic of Cancer, the high-pressure zone extends northeast, and the weather over France tends to be drier and sunnier.

On the islands themselves, that same anticyclone gives a very humid and very mild climate: regular and abundant rain, strong winds, four marked seasons, about 13 °C on average in winter and 24 °C in summer, according to the Geopark file. Snow falls only at altitude, often on Pico mountain.

From a bird, but the case is not closed. In Portuguese an açor is a raptor, Accipiter gentilis, which English calls the northern goshawk: the Priberam dictionary gives it so, with the Latin acceptor for origin. The Azores would then be the islands of the goshawks. The Geopark warns, however, that the origin of the name is the subject of several theories, and that the commonest associates it with the milhafres found on the spot, confused at the time with another raptor, the açor.

A witness from the time of the Infante Henry gives the old version. Diogo Gomes de Cintra writes in Latin that on the first island the crews found “muitos astures seu açores et multas aves”, many goshawks and many birds, and he says as much of São Miguel and Terceira. The Archivo dos Açores printed that text in 1878 with a Portuguese translation in which astures seu açores becomes milhafres ou açores: the translator slipped the buzzard into the sentence.

And a buzzard is indeed what lives there. The census by SPEA, the Portuguese society for the study of birds, names the endemic Azorean subspecies Buteo buteo rothschildi, known locally as milhafre or queimado, and states that it is the only resident diurnal raptor of the archipelago. The goshawk that is supposed to have given the islands their name does not live there: which is why the etymology is still argued over.