| São Miguel | |
| Ilha de São Miguel | |
| Island (Ilha) | |
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Pasturelands in the Picos region: the debris field that joined the Sete Cidades Massif and Água de Pau Massif that united the island of São Miguel
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| Official name: Ilha de São Miguel | |
| Name origin: Portuguese for Saint Michael | |
| Nickname: Ilha Verde | |
| Country | Portugal |
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| Autonomous Region | Azores |
| Islands | Eastern Group |
| Location | Azores Platform, Mid-Atlantic Ridge, Atlantic Ocean |
| Archipelago | Azores |
| Municipalities | Lagoa, Ponta Delgada, Povoação, Nordeste, Ribeira Grande, Vila Franca do Campo |
| Civil Parishes | (see text) |
| Highest point | Pico da Vara |
| - location | Planalto dos Graminhais, Nordeste |
| - elevation | 1,104.74 m (3,624 ft) |
| - coordinates | |
| Lowest point | Sea level |
| - location | Atlantic Ocean |
| - elevation | 0 m (0 ft) |
| Length | 63.54 km (39 mi), Northwest-Southeast |
| Width | 15.63 km (10 mi), Southwest-Northeast |
| Area | 744.55 km2 (287 sq mi) |
| Biomes | Temperate, Mediterranean |
| Geology | Alkali basalt, Tephra, Trachyte, Trachybasalt |
| Orogeny | Volcanism |
| Period | Holocene |
| Demonym | Micalense |
| Ethnic groups | Portuguese |
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Location of the island of São Miguel in the archipelago of the Azores
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| Wikimedia Commons: Island of São Miguel (Azores) | |
| Geographic detail from Instituto Geográfico Português (2010) | |
São Miguel Island (Portuguese pronunciation: [sɐ̃w miˈɣɛɫ]; Portuguese for Saint Michael), nicknamed "The Green Island", is the largest and most populous island in the Portuguese Azores archipelago. The island covers 759 km2 (293 sq mi) and has around 140,000 inhabitants, 45,000 of these people located in the largest city in the archipelago: Ponta Delgada.
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In 1427, São Miguel became the second of the islands discovered by Gonçalo Velho Cabral to be settled by colonists from continental Portugal. This date is uncertain, as it is believed that the island was discovered between 1426 and 1437 and inscribed in portolans from the middle of the 14th century.[1] In the early 15th century, Infante D. Henrique first authorized the settlement of the Azores, and many settlers from Estremadura Province, Alto Alentejo, Algarve and Madeira traveled to São Miguel, under the Carta Régia (a decree of the regency). The fertile soils and temperate climate attracted settlers from other countries, notably French people and cultural minorities such as Jews and Moors. Its geographic position and fertile soils permitted rapid economic development. The establishment of a military garrison made the island an obligatory port-of-call in the African and Asian commercial trade, while the export of sugar, and later orchil (a dye exported to Flanders for the making of cloth) stabilized the island's export trade.
The first capital of the island was Vila Franca do Campo, which was devastated by a major earthquake and landslides in 1522. The tragedy helped to elevate the importance of Ponta Delgada, eventually becoming the new capital in 1546.
During the 1580 Portuguese succession crisis, the people from São Miguel Island won the naval Battle of Vila Franca against a French squadron that supported the claims of the pretender António, Prior of Crato. During this time, the volcano Fogo 2 erupted, destroying the capital city and causing the death of 250 people.
With the Portuguese Restoration War (1640), the island regained its position as a commercial center, getting new contacts with Brazil, which was heavily colonized during this period. Some of the island’s historic buildings, including mansions and churches, date from this period. This architectural expansion was due to large profits earned from the production of oranges for export, mainly to Great Britain.
In 1831, during the Liberal Wars, after the landing of Liberal troops in Nordeste ordered by the future duke of Terceira, the resistance to the Absolutist regime on the Island was organized. In 1832, the Army, after declaring the Constitution and recognizing Maria II of Portugal as their queen, left Ponta Delgada. After the troubled period of the Liberal Wars, the previous economic expansion resumed, the port of Ponta Delgada was built, and also new crops such as tea, pineapple, and tobacco were introduced. The development of the fishing industry and the improvement of agricultural products have helped to boost the economy until the present day.
The island became the seat of the Presidency of the Autonomous Region of the Azores, and is the largest political-administrative center in the Azores.
São Miguel is bisected by many faults from the northwest to southeast in the direction of the Terceira Rift, a triple junction of the Eurasian, African and North American tectonic plates. This system is best expressed in the western part of the island with extensive geological formations, such as the Mosteiros Graben (along the western flank of the Sete Cidades Massif), the Ribeira Grande Graben (along the northern flank of the Água de Pau Massif), and the many cones and fissural structures along the interior of the island. In the ancient crater of Furnas the faults are aligned west-northwest to east-southeast. Zbysewsky (1959), among others (note references) identifies eight geomorphological structures on São Miguel that correspond to the formative features that built the island, including:
São Miguel comprises six volcanic zones, all are Quaternary in age except the last, which is partly Pliocene. From west to east these zones are: the trachyte stratovolcano of the Sete Cidades Massif; a field of alkali-basalt cinder cones and lava flows with minor trachyte; the trachyte stratovolcano of the Água de Pau Massif; a field of alkali-basalt cinder cones and lava flows with minor trachyte and tristanite; the trachyte stratovolcano of Furnas; and the Nordeste shield, which includes the Povoação caldera and consists of alkali basalt, tristanite and trachyte.[2] Dormancy ages for these regions include: 400 year for Sete Cidades, 145 for zone 2, 1150 for Água de Pau, and 370 for Furnas, while eruptions in the Nordeste have not occurred in the past 3000 years.[2]
These geomorphological structures have resulted from millions of years of compound growth that began in the eastern portion of the island; around 4 million years ago the Nordeste Volcano burst from the ocean floor in effusive and fissural eruptions. These eruptions were composed of basaltic lava flows and spatter cones whose products reached a height of 1,100 metres (3,600 ft) forming the mountainous region of Tronqueiro, Planalto dos Graminhais, Espigão dos Bois and Pico Verde (finding its maximum extent in Pico da Vara). But, about 950,000 years ago a secondary volcano system (Volcanic Complex of Povoação) supplanted the eruptions of the Nordeste Volcano, responsible for new basaltic lavas and pyroclastic deposits. With an age of 200,000 years the third volcano on São Miguel, the Água de Pau Volcano started erupting on the western flank of Povoação volcano in two phases. The first phase, composed of the older materials, erupted from lava flows and Trachyte pyroclasts, the secondary phase corresponded to volcanic products that began erupting 400,000 years ago. These latter deposits included pyroclastic, trachyte flows (lava and surges), mud flows and a mixture of basalts. In what would become the western portion of the island a fourth volcano formed: the Sete Cidades Volcano erupted 200,000 years ago and continued to erupt until about 36,000 years ago. Between 100,000 and 3,800 years ago fissural eruptions of integrated lava and basaltic pyroclastic deposits occurred in the center of the island between Água de Pau and Povoaçãp, forming the Fissural Volcanic System of Congro. These eruptions were explosive and fed by activities in the neighboring volcanic systems. At about 100,000 years a secondary system developed along the frontier of the Povoação volcano, the "Furnas Volcano" complex (the youngest volcanic system) in three phases mixing pyroclastic surges, trachytes, and lava flows, as well as explosive materials. Finally, two layers of deposits formed the Fissural Volcanic System of Picos between the volcanic Água de Pau and Sete Cidades from 31,000 years ago unifying the island. This formation integrated lavas, basaltic pyroclasts, tuff cones and trachyte domes into two layers (referred to as the Ponta Delgada and Penhal da Paz sub-depoists) and compiled to about 5,000 years ago.
The ancient laurisilva forest has mostly been replaced by cultivated fields and imported trees and plants, such as the ubiquitous cryptomeria trees. There are some hot springs (caldeiras), generally located in the center of the island, in the area stretching from Povoação to Nordeste.
The peak area between Sete Cidades and Fogo is a monogenetic volcanic field composed of 270 volcanoes. They are primarily made up of basaltic cones which were formed during Strombolian and Hawaiian-style eruptions. This is the part of the island with most recent volcanic activity. The youngest volcanoes are relatively well dated. It is estimated that 19 eruptions have occurred during the last 3,000 years. Several eruptions have been witnessed and recorded by people. The last one took place in the 17th century. The most famous eruption is known as Fogo 2, occurring in 1652.
The highest elevation on São Miguel is the Pico da Vara at 1,103 metres (3,619 ft). Lying at the eastern end of the island, it is the focus of a Special Protection Area containing the largest remnant of laurisilva forest on the island, which is home to the endemic and critically endangered bird, the Azores Bullfinch.
Similar to other islands in the archipelago, São Miguel is influenced by ocean currents and winds, and in particular, the cyclonic Gulf Stream. It functions as a moderating force in the islands, keeping temperatures hovering between 14 °C (57 °F) and 26 °C (79 °F) throughout the year. The island's location also makes it susceptible to many Atlantic storms, and precipitation tends to be elevated during the winter periods.
Owing to the predominance of volcanic cones and craters in the interior, human settlement has developed primarily along coastal and interior plains. In addition, there are several communities that have developed within ancient craters (such as Sete Cidades, Furnas or Povoação, river-valleys (such as Ribeira Chã, Pilar da Bretanha) or coastal deltas (Mosteiros). Regardless, these settlements were largely agrarian and concentrated around the parish churches and the many fertile parcels of land. The communities were largely isolated throughout the year, owing to the great distances and rough landscape of the island, and only became integrated with the development of the many road networks that circle and bisect the island. Two cities have developed, largely because the island was divided by mountainous volcanic cones in the interior: Ponta Delgada and Ribeira Grande. Administratively, the island is governed by five municipalities, with Ponta Delgada and Ribeira Grande having more administrative functions associated with their larger populations:
At the local government level, the municipalities include civil parish authority responsible for the provision of services and implementation of municipal initiatives. Based on the ecclesiastical limits established in the history of Portugal, the civil parishes are run by a president, treasurer and secretary at the head of a parish council. These presidents have municipal council standing and represent their constituencies. On the island of São Miguel there are 64 local area authorities, that include:
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