15.1 Introduction
15.1.1 Geographical and Geological Context of the Canary Islands
The Canary Islands are located in the Northeast Atlantic, between 27°–29° N and
14°–18° W. The Archipelago consists of seven major islands, four smaller islets
and numerous rocky outcrops (Table 15.1, Fig. 15.1). The islands are arranged
longitudinally along 450 km. Fuerteventura Island is only 90 km from the African
continent, La Palma is almost 400 km from it (Fernández-Palacios and Martín
Esquivel 2001a). The islands have a land surface area of 7,490 km
2 and 1,501 km
of coastline. The land surface and length of coastline vary in the different islands;
Tenerife is the largest in area and length of coastline (2,034 km
2 , 336 km), while
El Hierro has the smallest surface (269 km
2 ) and La Gomera the shortest length of
coastline (97 km).
From a geological point of view, the Canary Islands belong to the group of
‘‘oceanic islands’’, they emerge from the ocean floor and have their own structures
(insular edifice) completely independent of the continents. In fact, the Canary
Islands, except for Lanzarote and Fuerteventura that share the same insular edifice,
had independent origins from the others. The size of the islands’edifice is especially relevant since over 80 % of most islands is under water. On average, insular
edifices rise from a depth of 3,500 m. The depth is greater than 4,000 m for La
Palma and El Hierro (Carracedo 1988; Carracedo et al. 2001).
The origin of the islands dates back to about 20 million years, but there are also
important variations in age between islands (Table 15.1). In fact, while in some
islands the eruptive periods have ceased several million years ago, in others it has
continued up to the present, as indicated by the large number of historical eruptions (\500–600 years old). A good example of this volcanic activity is the recent
eruption off El Hierro Island that started in October 2011. The difference in the
ages between islands has important implications for the substrate morphology and
topography, both inland and underwater, since erosion and remodeling of insular
edifices are higher in older islands (Carracedo et al. 2001).
The abyssal plain between the islands is dotted by a large number of submarine
mountains and volcanoes. Most rise only a few hundred meters above the ocean
floor, but there are two mountains, the ‘‘Banco de La Conception’’ located north of
Lanzarote and the ‘‘Banco de Amanay’’ southwest of Fuerteventura, whose summit
is less than 100 m deep. In the past, when sea level was lower, these mountains
were above sea level and were true islands (Fernández-Palacios 2004). The current
submarine volcanism is now considered more important than terrestrial activity,
since recent seismic studies and dating of lava flows indicate the presence of active
submarine volcanoes in the western region of the archipelago (Carracedo 2001).
Due to the volcanic nature of the islands, their edifices have a significant slope,
thus the island platforms (shallow bottoms of gentle slope located between 0 and
100 m depth) are limited in area compared to the land surface (Mitchell 1998;
Masson et al. 2002). The extension of the island platforms largely depends on the
472
J. C. Hernández et al.
15.1.1 Geographical and Geological Context of the Canary Islands
The Canary Islands are located in the Northeast Atlantic, between 27°–29° N and
14°–18° W. The Archipelago consists of seven major islands, four smaller islets
and numerous rocky outcrops (Table 15.1, Fig. 15.1). The islands are arranged
longitudinally along 450 km. Fuerteventura Island is only 90 km from the African
continent, La Palma is almost 400 km from it (Fernández-Palacios and Martín
Esquivel 2001a). The islands have a land surface area of 7,490 km
2 and 1,501 km
of coastline. The land surface and length of coastline vary in the different islands;
Tenerife is the largest in area and length of coastline (2,034 km
2 , 336 km), while
El Hierro has the smallest surface (269 km
2 ) and La Gomera the shortest length of
coastline (97 km).
From a geological point of view, the Canary Islands belong to the group of
‘‘oceanic islands’’, they emerge from the ocean floor and have their own structures
(insular edifice) completely independent of the continents. In fact, the Canary
Islands, except for Lanzarote and Fuerteventura that share the same insular edifice,
had independent origins from the others. The size of the islands’edifice is especially relevant since over 80 % of most islands is under water. On average, insular
edifices rise from a depth of 3,500 m. The depth is greater than 4,000 m for La
Palma and El Hierro (Carracedo 1988; Carracedo et al. 2001).
The origin of the islands dates back to about 20 million years, but there are also
important variations in age between islands (Table 15.1). In fact, while in some
islands the eruptive periods have ceased several million years ago, in others it has
continued up to the present, as indicated by the large number of historical eruptions (\500–600 years old). A good example of this volcanic activity is the recent
eruption off El Hierro Island that started in October 2011. The difference in the
ages between islands has important implications for the substrate morphology and
topography, both inland and underwater, since erosion and remodeling of insular
edifices are higher in older islands (Carracedo et al. 2001).
The abyssal plain between the islands is dotted by a large number of submarine
mountains and volcanoes. Most rise only a few hundred meters above the ocean
floor, but there are two mountains, the ‘‘Banco de La Conception’’ located north of
Lanzarote and the ‘‘Banco de Amanay’’ southwest of Fuerteventura, whose summit
is less than 100 m deep. In the past, when sea level was lower, these mountains
were above sea level and were true islands (Fernández-Palacios 2004). The current
submarine volcanism is now considered more important than terrestrial activity,
since recent seismic studies and dating of lava flows indicate the presence of active
submarine volcanoes in the western region of the archipelago (Carracedo 2001).
Due to the volcanic nature of the islands, their edifices have a significant slope,
thus the island platforms (shallow bottoms of gentle slope located between 0 and
100 m depth) are limited in area compared to the land surface (Mitchell 1998;
Masson et al. 2002). The extension of the island platforms largely depends on the
472
J. C. Hernández et al.