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Case Study 13

The Azores

Volcanic Islands in the Atlantic

Henry Gaudru the archipelago (around 46km long and 15km
wide). The main settlements are the capital
Introduction Madalena, São Roque do Pico and Lajes do Pico;
the total population is around 15,000 inhabitants.
The nine volcanic islands of the Azores are located Tourism is the main industry in Pico Island, but it
in the Atlantic Ocean about two hours flying time does not seem very crowded as yet. Pico is the
and 1500km from Lisbon (Portugal), and about most mountainous island in the Azores and
five hours flying time or 3900km from the eastern contains the most dramatically beautiful landscapes,
coast of North America (Azores.com, 2009a). The including Pico Alto, Portugal’s prominent
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Azores have a total area of 355km , sit on top of stratovolcano, which at 2352m is the highest peak
the Mid-Atlantic Ridge, where mountains (Global Volcanism Program, 2009) and can be seen
sometimes reach above sea level (Encyclopaedia from all over the island and from peaks on the
Britannica, 2009), thus forming islands of volcanic other Azores islands (Figure CS13.1).
origin. The Azores have been created by Pico volcano overlies an older linear volcano
outpourings of lava from the ocean floor, due to with a number of flank cones making up most of
the high level of activity in the area which is a the 48km long island. The volcano rises 3500m
result of three major tectonic plates meeting at above the surrounding ocean floor and has a
this point (Siebert and Simkin, 2002). The North subaerial volume of 97km as compared with the
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American Plate to the north-west of the Azores is total subaerial volume of Pico Island of 207km .
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gradually drifting west, the Eurasian Plate to the The conical Pico volcano is dominantly basaltic
north-east is drifting east and south and finally the and developed above the Montanha volcanic
African Plate is drifting east and north. The small complex on the eastern side of Pico Island with a
Azores Microplate, which is drifting westwards, 500m wide summit crater and a small steep sided
further complicates the picture. The last volcano cone (Global Volcanism Program, 2009). Historical
to erupt in the archipelago was the Capelinhos eruptions have been limited to the sides of Pico
volcano (Vulcão dos Capelinhos) in 1957, in the volcano as well as to the south-east-trending rift
western part of Faial Island, increasing the size of zone, the São Roque Piedade volcanic complex,
that island by 2.4km.
which is covered with pyroclastic cones. During
1562–64 an eruption from the south -east rift
Pico Volcano Natural Reserve zone formed lava flows that reached the northern
Pico Island is the furthest south of the central coast. An erupting nearby vent produced lava
cluster of the Azores and is the second largest in flows that moved into the sea on the south side of

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