Terceira island

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  Referred to as the “Ilha Lilás” (the “lilac” or “violet” island), Terceira (Portuguese pronunciation: [tɨɾˈsɐjɾɐ]) is an island in the Azores archipelago, in the middle of theNorth Atlantic Ocean. It is one of the larger islands of the archipelago, with a population of 56,000 inhabitants in an area of approximately 396.75 km². It is the location of the historical capital of the archipelago, the Azores' oldest city and UNESCO Heritage Site (Angra do Heroísmo), the seat of the judicial system (Supreme Court), main base of the Azores Air Zone Command (Commando da Zona Aérea dos Açores) Base Aérea nº 4 and to a United States Air Force detachment.
  

  

  
  
  
  

  The island of Terceira consists of four overlapping stratovolcanoes built over a geologic structure called the Terceira Rift: a triple junction between the Eurasian, African and North American tectonic plates. These volcanic structures rise from a depth of over 1,500 metres (5,000 ft) from the floor of the Atlantic Ocean. Radiocarbon dating of eruptive units, in support of geologic mapping, has improved the known chronology of Middle to Late Pleistocene and Holocene volcanic activity on the island of Terceira, Azores, defining the east-to-west progression in stratovolcano growth. These have commonly resulted in a classification of the eruptive events into the following structures:

  • Cinco Picos Volcanic Complex - the oldest on Terceira (defined by the Serra do Cume), which completed its main sub-aerial activity by about 370–380,000 years ago. Collapse of the upper part of the stratovolcanic edifice formed an enormous 7 × 9 km caldera about 370,000 years ago. Post-caldera eruptions of basalt from cinder cones on and near the caldera floor and trachytic pyroclastic flow and pumice fall deposits from younger volcanoes west of Cinco Picos have refilled much of the caldera producing an almost-uninterrupted fertile plain.
  • Guilherme Moniz Volcanic Complex - the southern portion , in the central part of the island, began erupting about 100,000 years later (about 270,000 ka) and produced trachyte domes (approximately 808 m/2651 ft in altitude), flows, and minor pyroclastic deposits for another 100,000 years (until at least 111 ka). The highest point along the caldera rim reaches 623 metres (2,044 ft). The northern portion of the Caldera is less well exposed, but reflects a similar age range. The northwest portion of the caldera was formed sometime after 44 ka. Several well-studied ignimbrites that blanket much of the island likely erupted from Guilherme Moniz Volcano.
  • Pico Alto Volcanic Complex - Center, a tightly spaced cluster of trachyte domes and short flows, is a younger part of Guilherme Moniz Volcano. Stratigraphic studies and radiocarbon analysis suggest that most of the Pico Alto eruptions occurred during the period from about 9000 to 1000 years BP.
  • Santa Barbara Volcanic Complex - the youngest stratovolcano on Terceira, began erupting prior to 29,000 years ago, and has been active historically, comprises the western end of the island and at its highest point is 1,023 m (3,356 ft). This stratovolcano is surrounded by several domes and coulee trachyte formations that occupy the volcano's caldera and along various alignments of the volcano's flanks.
  • Fissural Zone - Connecting the eastern portion of Santa Bárbara, the western frontier of Pico Alto and Guilherme Moniz exist a grouping of fissural volcanoes and basaltic cones (Hawaiian and Strombolian), the youngest of which formed about 15,000 years ago. The only historical eruptions occurred in 1761, along a fissure on the eastern face of Santa Bárbara, and in 1867 and between 1998–2000 from submarine vents off the western coast (Serreta (Azores)). The groupings of volcanic structures on the island are aligned along a northwest-southwest and west-northwest-east-southeast orientation that extends to the submarine vents/volcanoes towards the eastern basin of Graciosa, including geomorphological alignments of smaller volcanic structures (including both basaltic and trachytic cones)
  • Island tectonics are highlighted by two great faults in the northeast corner (the Lajes and the Fontinhas faults), the Lajes Graben has been responsible for severe seismic events. Historically, both faults have produced earthquakes that are relatively shallow, strong and responsible for the destruction of property in the northeastern corner (specifically in 1614 and 1841). During the 1614 event, whose epicenter was located along the Lajes fault eight kilometers offshore, recorded magnitudes for the earthquake were between 5.8 and 6.3 on the Richeter scale (Wells and Coppersmith,1994). Both the Lajes and Fontinhas faults are separated by three kilometers). A second, less-developed, graben is located on the southeast of the Santa Bárbara stratovolcano. This feature is marked by trachyte domes and crosses from the coast at Ponta do Queimado (from the historical basin of Serreta (Azores)) to the cliffs, faults, basaltic lava and fissural eruptions near the center of the island.
    
    
    
    The western part of Terceira Island is more heavily forested than the eastern part, due to the prevailing westerly winds bringing increased precipitation to that side, resulting in forests of Cryptomeria (Cryptomeria japonica). Other geomorphological points of interest include the plains of Achada, the mounts near Santa Bárbara, the small lakes of Lagoa das Patas and Lagoa da Falca. The northern coast is an area marked by evidance of volcanic activity with several "mistérios" (lava fields), the swimming pools of Biscoitos, while the centre of the island is highlighted by the Algar do Carvão and Furnas do Enxofre(dormant and active volcanic forms) that are popular with tourists and geologists. Most of the island is ringed by coastal cliffs about 20 m (60 ft) high, except on the south coast near Angra do Heroísmo. Here, an eruption of basaltic lava in shallow water formed the tuff cone of Monte Brasil, which protects and shelters the harbor of the island's capital. The cone is about 1 km (0.6 mi) in diameter and rises 205 m (673 ft) above the western side of the harbor.
    Away from the coast, Terceira is a wild and hilly landscape with the availability of many walking and hiking trails. Much of the interior of the island is a nature reserve; from the heights of the Serra do Cume to the slopes of Santa Bárbara, there are several paths along the patchwork of small farms, stonewalls and forests that will occupy the naturalist.
    Much like other islands of the Azores, human settlement was dictated by the geomorphology of the terrain. The number of volcanic cones and the stratovolcanos that occupy the major part of the interior of the island, forced most communities along the coastal lowlands and river-valleys, producing a "ring" of urbanization that circles the island, usually following the Regional Road network. These communities began as agricultural enclaves, based on subsistence farming and a patchwork of hedged parcels of land.^[4] The nuclei of these communities were the religious parishes, and the churches that dot the landscape of the island.
    
    
    
    Administratively, Terceira is divided (along an irregular diagonal frontier from north-northwest to sout-southeast) into two municipalities: Angra do Heroísmoand Praia da Vitória. The municipality of Angra do Heroísmo is located in the southern half of the island, and includes the historical town of Angra, its suburban communities and many of the coastal resort communities (such as Porto Martins). Praia da Vitória is highely concentrated in the north-northeast corner of the island along an axis between Cabo do Porto and Lajes; its generally considered the industrialized center of the island, location of one of the two main commercial ports, the international airport and many of the associated businesses associated with the Air Force base. Apart from the uninhabited areas at the center of the island, the northwestern and portions of the western coast are sparsely populated, apart from small agglomerations of homes along the roadways. Within the municipal framework communities are subdivided into local civil parishes (19 in Angra do Heroismo and 11 in Praia da Vitória), and managed by the executive (that includes a President and cabinet) and the civil committee (with its chairperson and assembly) of the Junta Freguesia.
  
  

Graciosa Island

Graciosa Island (Portuguese pronunciation: [ɡɾɐsiˈɔzɐ]) (literally "graceful" or "enchanting" in Portuguese) is referred to as the White Island, the northernmost of the Central Group of islands in the Azores. The ovular Portuguese island has an area of 60.84 km², a length of 10 km and a width of 7 km. It is a volcanic island, dominated by a 1.6 km wide central caldera (the Caldeira) located in the southeast.

Graciosa Island is situated in the northwest tectonic structure called theTerceira Rift, oriented southeast to northwest and coincident with the orientation of the archipelago. The presence of the Rift has deformed Graciosa into an elongated oval form 12.5 km long by 8.5 km wide.

The coast is rough and rocky but generally low, except in the northwest along the Serra Branca (where the cliffs are 200 meters high). There are two shallow bays, situated in the southeast and southwest corresponding to fishing ports in Vila da Praia and Folga, respectively. Along the northeast coast there are several smaller coves near Santa Cruz da Graciosa that were used as ports but are now abandoned, and the older whale and commercial port in Barra, now used as a recreational zone.

 The interior of the island is generally flat and dotted by numerous volcanic cones, with a southern portion of the island higher in altitude. The island is divided into four geomorphological zones:

• The Caldeira Massif, in the extreme southeast of the island, comprising a well preserved volcano and caldera;
• Serra das Fontes, located along the northeast coast, a zone of cliffs and escarpments formed by local tectonics;
• The Serra Dormida and Serra Branca Volcanic Complexes, occupying a third of central island, and weathered by local tectonics;
• The Santa Cruz Platform, occupying the northwest of the island, characterized by a relief that is gently sloping (approximately 50 meters) and punctuated by several volcanic cones.
• Volcanism on Graciosa was predominantly characterized by low explosivity, although there appear some deposits that show indications of elevated explosivity in its geological record. Aerial volcanism had its beginning approximately 600,000 years ago with the formation of a shield volcano, which is still visible in the Volcanic Complex of Serra Branca (the oldest part of the island). This was followed by periods of explosivity, related to the faults that traverse the zone, forming numerous cones that constitute a major part of the Serra Dormida and Serra das Fontes region. The type of volcanism altered radically around 350,000 years ago with the formation of the central volcano (and later caldera) associated with a different magma chamber, resulting in greater explosivity and giving rise to thick sheets of pumice that layered Serra Branca. The formation of the Santa Cruz Platform comes from the more recent geological volcanism associated with lower explosive basaltic eruptions resulting in numerous cones and sub-aerial deposits that cover the center and northern portions of the island. This phase evolved towards the southeast forming the Caldera Massif and many of the islets and submarine mounts along the coast. The last phase of the geological history of Graciosa occurred 2,000 years ago, forming Pico Timão and the basaltic flows that are located in the surrounding areas.
• The territory of Graciosa Island consists of one municipality, Santa Cruz da Graciosa (4,780 inhabitants in 2001), divided into four civil parishes:
• Santa Cruz - the seat of the municipality and principal urbanized population on the island, located on eastern coast;
• São Mateus da Praia - a historic village and once municipal seat, until the it was unincorporated in the 19th century;
• Guadalupe - the principal rural population on the island;
• Luz - civil parish better known locally as "Sul" (South), located along the southern coast of the island.

       Owing to concentration of agriculture, animal husbandry and dairy industries, the island has maintained the relatively rural and tranquil character. The island's fields produce various fruits, wines, grass-fed beef and dairy cattle as well as cheese and other dairy products. The construction of a commercial port and the 1980 construction of the Graciosa Aerodrome has retained the islands links to the archipelago while strengthening exports and importing goods and services. In addition to this, the island has benefited from infrastructural investments that have included the re-qualification of the secondary school, the construction of a new milk factory and fishing port. As well, improvements to the recreational areas in Praia and refurbishment of the Thermals in Carapacho, the construction of a new hotel and Medical Center have been done in order to improve both the tourist industry and support the local community.

Pico island

Pico Island (Ilha do Pico, Portuguese pronunciation: [ˈiʎɐ du ˈpiku]), is an island in the Central Group of the Portuguese Azores noted for its eponymous volcano,Ponta do Pico, which is the highest mountain in Portugal, the Azores, and the highest elevation of the Mid-Atlantic Ridge. In the tradition of the Portuguese poet, Raul Brandão, Pico is referred to as the Ilha Preta ("Black Island"), for its black volcanic earth, responsible for its UNESCO-designated historical vineyards that allowed the development of the island.

The island is 17.5 km south ofSão Jorge and just 7 km east ofFaial, in the Cental Group of islands, an area that is colloquially known as o Triangulo (The Triangle). Pico is 46 kilometers long, and at its maximum extent about 16 kilometers wide, rising from its center to the west in the summit of the stratovolcano of Pico; making it the second largest of the Azores islands. Along the central plain of volcano cones to the eastern coast the landscape is pitted with the remnants of craters and lake-filled cones, and dominated by the ancient volcano of Topo. Geomorphologically, the island is composed of three units:

• Topo Volcano - Located on the southeastern coast, it corresponds to an ancient volcano destroyed by erosion and landslides;
• Plain of Achada - Extending from Topo to the stratovolcano the Achada Plain is an axial zone comprising spatter and lava cones along a mountainous ridge filled with lake-filled craters, dense scrub and forests. Cones in this region are oriented along a west-northwest and south-southeast axis along a path east to west between the other volcanic structures;
• Pico Volcano - It occupies the western portion of the island, and corresponds to the central volcano with a 2341 meter altitude. Along its flanks are diverse lava and spatter cones that are formed along radial fractures and faults.

Generally, the island of Pico's tectonic structures are oriented along a west-northwest to east-southeast and a northeast to southwest axis. The main axis controls the main structures, especially the main mountain of Pico, while the secondary axises affect the radial fractures and faults along the central plain and eastern volcano.

Similar to the geomorphological structures described above, the volcanic landforms have been identified by Madeira (1998) in the following units:

• Volcanic Complex of Lajes - pertains to the oldest volcanic structures, comprising volcanoes, lavas and debris that are between 35-300,000 million years old; it makes up the structures of the eastern part of the island, including the ancient volcano of Topo.
• Volcanic Complex of Calheta de Nesquim - dating to about 230,000 million years ago, this is a fissural zone of cones and basaltic lavas, associated with the Achada Plain, and the many faults along the central plateau of the island.
• Volcanic Complex of Madalena - the most recent volcanic complex, with both geological and historical eruptions; it includes the basaltic stratovolcano of Pico, but also many of the cones, faults and lava fields that circle the 2,351 meter summit.

The last volcanic eruption (which is debatable) occurred in 1963, in a small submarine eruption off the northwest coast (north of Cachorro in Santa Luzia). Prior to this, major volcanic activity was only evident in lava fields generated in the areas of Prainha(1562–64), Santa Luzia (1718), São João (1718) and Silveira (1720). The paths of the lava flows are still visible, those in the 16th Century and 1718 were particularly substantial, extending for over 10 km. Today, the only visible evidence of active volcanism appears on the summit of Pico, in the base and interior of the Piqueninho (the mini-peak on the summit); there are irregular emissions from cracks in this zone. Additionally, there are emissions on the eastern flanks between 1500 and 2000 meters altitude. There have also been found areas of de-gasification along the a fault associated with the Lagoa do Capitão and another in the Topo Volcano, as well as a spring rich in CO2 in the area of Silveira.

Pico, much like the other islands, are susceptible to seismic events, although their epicenters have primarily been localized in the Faial-Pico or Pico-São Jorge Channels. The strongest earthquake registered in the last 30 years occurred on July 9, 1998, and had its epicenter 5 kilometers northeast of Ponta da Ribeirinha, on the island of Faial, reaching a 5.8 magnitude. It was felt on Pico, with a maximum intensity level of VII on the Mercalli scale; some homes were damaged and possessions were buffeted. Other violent earthquakes which have affected the island include: the 1957-58 seismic events associated with the eruption of the Capelinhos volcano (on Faial), the February 1964 earthquake on the island of São Jorge, and the 1926 earthquake, whose epicenter was registered in the Faial-Pico Channel.

The island supported a substantial whaling industry until 1980. The position of the island on the Mid-Atlantic Ridge means that deep water is very close. Active industries include tourism, shipbuilding and wine production. Landscape of the Pico Island Vineyard Culture has been a UNESCO World Heritage Site since 2004. It has several notable wines, that are commercialized in Portugal and exported abroad.

AZORES ISLANDS

The Azores (English pronunciation: /əˈzɔrz/ ə-ZORZ ; Portuguese: [ɐˈsoɾɨʃ], Açores) is a Portuguese archipelago in the Atlantic Ocean, about 1,500 km (930 mi) west from Lisbon and about 3,900 km (2,400 mi) east from the east coast of North America. The Monchique Islet onFlores Island, located at 31° 16' 24" W is regarded as the westernmost point in Europe, even though from a geological standpoint the two westernmost Azorean islands (Flores and Corvo) actually lie on the North American plate. The archipelago, and economic exclusion zone, forms the Autonomous Region of the Azores, one of the two autonomous regions of Portugal. Its main industries are: agriculture,dairy farming (for cheese and butter products primarily), minor livestock ranching, fishing and tourism, which is becoming the major service activity in the region. In addition, the government of the Azores is responsible for employing a large percentage of population directly or indirectly in many aspects of the service and tertiary sectors.

The nine major Azorean islands and Formigas extend for more than 600 km (373 mi) and lie in a northwest-southeast direction. The vast extent of the islands defines an immense exclusive economic zone of 1,100,000 km² (420,000 sq mi). The westernmost point of this area is 3,380 km (2,100 mi) from the North American continent. All of the islands have volcanic origins, although some, such as Santa Maria, have had no historical activity since the islands were settled. Mount Pico, on the island of Pico, is the highest point in Portugal, at 2,351 m (7,713 ft) in altitude. Generally, the Azores are actually the peaks of several of the tallest mountains on the planet, breaking the surface in the mid-Atlantic (as measured from their base at the bottom of the ocean).

In 1877, Samuel Clemens, who found fame under his moniker Mark Twain, wrote of the Azores, as follows:

I think the Azores must be very little known in America. Out of our whole ship’s company there was not a solitary individual who knew anything whatever about them. Some of the party, well read concerning most other lands, had no other information about the Azores than that they were a group of nine or ten small islands far out in the Atlantic, something more than halfway between New York and Gibraltar. That was all.

Because these once uninhabited, remote islands were settled sporadically over a span of two centuries, their culture, dialect, cuisine and traditions vary considerably from island to island. Farming and fishing are key industries that support the Azorean economy.