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.
