Geology of the Canary Islands

and ocean bathymetry The Canary Islands are a , east–west aligned archipelago of volcanic islands in the eastern part of the North Atlantic Ocean, off the coast of Northwest Africa. Geologically, there are seven main islands in the Canary Islands; from east to west they are Lanzarote, Fuerteventura, Gran Canaria, Tenerife, La Gomera, La Palma, and El Hierro. Close to the coasts of the main islands, there are some minor islands and named islets including: • near Lanzarote: the Chinijo Archipelago (La Graciosa, Alegranza, Montaña Clara, Roque del Este, and Roque del Oeste); • near Fuerteventura: Lobos; • near Tenerife: Roques de Anaga, Roque de Garachico; • near Gran Canaria: Roque Melenara; • near La Gomera: El Roquillo; • near La Palma: Roque de Santo Domingo, Roque de las Tabaidas, Roque del Guincho; • near El Hierro: Roques de Salmor; There are also numerous unnamed islets. The seven main Canary Islands originated as separate submarine seamount volcanoes on the ocean floor, which is deep in the Canarian region. Lanzarote and Fuerteventura are separated by an , ocean strait. Both islands are parts of a volcanic ridge called the Canary Ridge. These two islands have sometimes been a single island in the past when worldwide sea level was lower than its present level, for example during the Last Glacial Maximum about 20,000 years ago. The single island is sometimes referred to as Mahan. The volume of volcanic rock that has built up the Canary Islands to thousands of metres above the ocean floor is about ; 96% of this lava is hidden below sea level and 4% () is above sea level. The western islands have more of their volume (7%) above sea level than do the eastern islands (2%). ==Regional setting==

The Canary Islands are built upon one of the oldest regions of Earth's oceanic crust (175–150 Ma), The rocks under and in the Canary Islands are a record of multiple periods of volcanic activity: • Starting about 180 Ma (million years ago), the oceanic crust of the North Atlantic Ocean was formed; it consists of igneous rocks (plutonic rocks overlain by volcanic rocks) that were gradually covered by layers of sedimentary rocks. The igneous part of the oceanic crust was formed by seafloor spreading at the divergent plate boundary between the North American and African plates, as a result of the breakup of the supercontinent Pangaea; in the Canary Islands region, this occurred in the Jurassic Period. North America and Northwest Africa separated while the Atlantic Ocean grew between them. Although this volcanic activity formed the ocean floor on which the Canary Islands were later formed, this seafloor spreading type of volcanic activity was not involved in the formation of the islands. • Starting about 70 Ma, volcanic activity in the Canary Volcanic Province has occurred at numerous seamounts across the region now occupied by the Canary Islands as well as an area of the ocean floor up to north of the Canary Islands. The northernmost of this group of seamounts, Lars seamount (about north of Lanzarote), has been dated to 68 Ma. The seamounts are progressively younger southwestwards towards Lanzarote. Some seamounts developed into islands: first to emerge above sea level, at about 30 to 25 Ma, were the Selvagen Islands ( north of where the Canary Islands would later form). Then, each of the Canary Islands emerged as an island between 20.2 Ma and 1.1 Ma. Volcanic activity in the Canary Volcanic Province has continued to the present day. ==Island development stages==

has cut ravines and canyons (known locally as barrancos) into the lava piles of some of the islands, as in this example at Barranco de Tirajana, Gran Canaria. The geological features of the Canary Islands place this island group at one end of a spectrum of types of intraplate volcanic oceanic islands that form in deep parts of the oceans, far from tectonic plate boundaries; the Hawaiian Islands are at the other end of this spectrum. Intraplate volcanic oceanic islands follow a sequence of development stages. The sequence of stages was originally recognised, during the 1930s and 1940s, in the Hawaiian Islands, where eight stages were defined. • submarine (seamount) stage (El Hijo de Tenerife seamount) • shield-building stage (La Palma, El Hierro) • erosional stage (La Gomera) • post-erosional (or rejuvenation) stage (Tenerife, Gran Canaria, Lanzarote, Fuerteventura) The Canary Islands differ from some other volcanic oceanic islands, such as the Hawaiian Islands: for example, the Canary Islands have stratovolcanoes, compression structures and a lack of significant subsidence. the distance between Lanzarote and Fuerteventura was also small enough for some of their shield volcanoes to overlap as they grew, forming a single volcanic ridge ==Age==

From about 70 Ma to 20.2 Ma, all the volcanic activity in the Canary Islands region occurred as underwater eruptions and the islands did not yet exist. Eventually, enough lava accumulated at particular locations to form each island of the Canary Islands archipelago. The age of the first underwater eruptions differs from island to island; for example, the first underwater eruptions at La Gomera were at more than 12 Ma but at La Palma they were at 4 Ma. Seamount stage rocks are not exposed on Lanzarote, Tenerife, Gran Canaria and El Hierro, which has hindered dating of the earliest underwater volcanic activity at these islands. The age of the oldest subaerially-erupted lavas on each island decreases from east to west along the island chain: Lanzarote-Fuerteventura (20.2 Ma), ==Geological map==

, 2016 (text in Spanish)|alt=Geological map of the Canary Islands Translation of Spanish text in the map: • Geología de las islas Canarias = Geology of the Canary Islands • Volcanismo = Volcanism • Océano Atlántico = Atlantic Ocean • Erupciones históricas = Historical eruptions • Volcanismo reciente = Recent volcanism • Volcanismo plioceno-pleistoceno = Pliocene-Pleistocene volcanism • Volcanismo mioceno = Miocene volcanism • Formaciones intrusivas = Intrusive formations • Complejo basal = Basal complex • Formaciones sedimentarias = Sedimentary formations • Conos volcánicos = Volcanic cones • Calderas y estructuras calderiformes = Calderas and calderiform structures • Nota: La erupción de El Hierro ocurrida en octubre de 2011, se considera histórica como cualquier erupción en la que hay documento escrito sobre su ocurrencia = Note: The eruption of El Hierro that occurred in October 2011 is considered historical, as is any eruption of which there is a written document about its occurrence • Fuente = Source • Actualización erupción de El Hierro = El Hierro eruption update ==Rock types==

Igneous rocks of volcanic rocks of the Canary Islands. The chemical compositions of 1,869 rocks are in the area outlined in red. The blue area roughly corresponds to alkaline volcanic rocks. The yellow area roughly corresponds to sub-alkaline volcanic rocks. ) where bubbles of gas were trapped within the lava when it was molten, from Lanzarote (length: ) In the Canary Islands, igneous rocks of the alkaline magma series are common, while rocks of the sub-alkaline tholeiitic magma series are rare. La Gomera and La Palma. Apart from some islands of Cape Verde (another volcanic island group in the Atlantic Ocean, about south-west of the Canary Islands), Fuerteventura is the only oceanic island known to have outcrops of carbonatite. On Fuerteventura, the carbonatite occurs as igneous intrusions. Sedimentary rocks Minor deposits of sedimentary rocks outcrop on the Canary Islands. They consist of calcrete/caliche, sandstone, conglomerate, aeolianite, and limestone. Metamorphic rocks Some metamorphic rocks are exposed on the Canary Islands. The structurally deepest parts (the basal complexes) of Fuerteventura, La Gomera, and La Palma include hydrothermally metamorphosed oceanic crust rocks and lower seamount rocks that were altered from their original igneous and sedimentary rock types and folded before the three islands emerged. These rocks were subjected to pressures and temperatures corresponding to zeolite, prehnite-pumpellyite and greenschist facies. These metamorphic rocks have been uplifted and then exposed by erosion of younger overlying rocks. There are small amounts of migmatite and hornfels that outcrop in contact aureoles bordering igneous intrusions in the Basal Complex of Fuerteventura. Some sedimentary rocks of the uppermost oceanic crust under Lanzarote were thermally metamorphosed by heat from intrusion of magma into the sedimentary rocks. The original sandstones and shales were transformed into quartzite and slate respectively. Later volcanic eruptions have transported fragments of these quartzites and slates onto the island's surface as xenoliths within basaltic lava. ==Origins of volcanism==

Several hypotheses have been proposed to explain the volcanism of the Canary Islands. Two hypotheses have received the most attention from geologists: • The volcanism is related to crustal fractures extending from the Atlas Mountains of Morocco. • The volcanism is caused by the African plate moving slowly over a hotspot in Earth's mantle. A hotspot (the Canary hotspot) is the explanation accepted by most geologists who have studied the Canary Islands in the last few decades. A relatively hot mantle plume associated with this hotspot is thought to be rising through the mantle under La Palma and El Hierro. Also, seismic tomography has revealed the existence of a region of hot rock extending from the surface, down through the oceanic lithosphere to a depth of at least in the upper mantle. Another line of evidence is the east-to-west decrease in age of the youngest sedimentary rocks under each island. ==Volcanic eruption distribution==

According to the Smithsonian Institution's Global Volcanism Program, , seventy-five confirmed volcanic eruptions have occurred in the Canary Islands in the Holocene Epoch (the last 11,700 years of Earth's geological history). Fifteen of these eruptions have occurred since 1490; In the last 500 years, a volcanic eruption has occurred somewhere in the island chain, on average, every 30 to 35 years. An eruption on Tenerife, about 2,000 years ago, is the largest Canarian eruption of the Holocene Epoch. The largest volume and longest duration historical eruption in the Canary Islands occurred in the early 18th century on Lanzarote. The following table shows the distribution of volcanic eruptions during the last 11,700 years in the Canary Islands: Tenerife and La Palma comparison During the last 10,000 years, Tenerife and La Palma have been the two most volcanically active Canary islands. The bar chart compares the number of confirmed volcanic eruptions (vertical y-axis) at different stages during this time span (horizontal x-axis). ==Lanzarote==

Volcanic activity at Lanzarote started during the Oligocene Epoch at 28 Ma. For about the first 12 million years, the lava pile of a submarine seamount built up from the ocean floor. Then, in the Miocene Epoch, from 15.6 Ma to 12 Ma, the Los Ajaches subaerial shield volcano grew as an island on top of the seamount, in an area corresponding to present-day southern Lanzarote. The edifices gradually merged to form a single island, Lanzarote, at about 4 Ma. Today, although the lavas of Los Ajaches volcano are now mostly covered by calcrete, the eroded remains of the two shield volcanoes are preserved in southern and northern Lanzarote respectively, with small outcrops of the central edifice occurring between them. A terrestrial sediment layer, around thick, between basalt layers on the Famara massif in northeast Lanzarote, dates to the early Pliocene Epoch around 4 Ma. The terrestrial sediment layer consists of calcarenite, clay-rich marl, and breccia. These sediment layers were formed on a sandy flat plain, when the island was likely around in area. It preserves fossils of insect eggs, land snails, snake vertebrae, as well as tortoise and bird eggshells. At about 2.7 Ma, in the late Pliocene Epoch, the rejuvenation stage began. It produced much less lava than the earlier shield stage, mainly at the Montaña Roja and Montaña Bermeja volcanoes in southern Lanzarote. Geologically recent examples of Lanzarote's rejuvenation stage volcanism include eruptions at Montaña Corona (about 21,000 years ago), Timanfaya (1730–1736) and Tao/Nuevo del Fuego/Tinguatón (1824). The Timanfaya eruption (1730–1736) erupted more than one billion cubic metres () of lava, and a large volume of pyroclastic tephra, from more than 30 volcanic vents along a fissure in western Lanzarote. The lava flows cover one quarter of the island (an area of about ) with some of the flows reaching about in thickness. It is the largest historical eruption in the Canary Islands, and the third largest subaerial fissure eruption of basaltic lava on Earth in the last 1,100 years. Almost all the volcanic rocks of Lanzarote are basaltic. ==Fuerteventura==

, Fuerteventura Fuerteventura is situated on Mesozoic oceanic crust, about from the edge of the African continental shelf and about from the African mainland, making it the Canarian island closest to Africa. Due to its old age, the oceanic crust at Fuerteventura is relatively rigid and this has prevented subsidence and allowed weathering and erosion to expose deep levels of the island's geological structure. The two main rock sequences of Fuerteventura are (1) a lower, older (Cretaceous to early Miocene) sequence of sedimentary, plutonic and submarine seamount volcanic rocks with intrusive dykes, often called the "Basal Complex", which is unconformably overlain by (2) a younger sequence of Miocene, Pliocene and Quaternary subaerial volcanic rocks. The oldest rocks of Fuerteventura are a set of mafic plutonic rocks, marine sedimentary rocks and volcanic rocks, which are intruded by igneous dykes. Fuerteventura's first alkaline magmatism intruded plutonic rocks into the oceanic crust at about 70 Ma. In the early Miocene, volcanic activity transitioned from submarine to subaerial while the volcanic edifice was gradually built up above sea level. Fuerteventura has the oldest subaerial volcanic rocks of the Canary Islands, These shield volcanoes erupted mostly basaltic and trachybasaltic lava flows. (foreground cliff height is approximately ) In the late Miocene (from about 11.5 Ma), there was a pause in volcanic activity (the erosional stage). Minor volcanic eruptions resumed in the Pliocene, at about 5.1 Ma (the rejuvenation stage) and they continued sporadically into the Quaternary, with basaltic lava flows dominating again. The most recent volcanic eruption on Fuerteventura that has been dated occurred 134,000 years ago in the Middle Pleistocene. ==Gran Canaria==

deposit, Gran Canaria After early Miocene submarine volcanic eruptions created a seamount, subaerial volcanic activity at Gran Canaria occurred in three phases: shield stage (middle- and late-Miocene, 14.5 to 8.5 Ma), erosional stage (late Miocene, 8.5 to 5.3 Ma) and rejuvenated stage (Pliocene to Quaternary, 5.3 Ma to present). The shield stage started with an early phase of eruptions of basaltic lava flows, from 14.5 to 14.1 Ma, which built the main subaerial shield volcanic edifice that forms three quarters of the subaerial volume of Gran Canaria. This was followed by a later phase, from 14.1 to 8.5 Ma, of explosive volcanic eruptions of differentiated felsic lavas (phonolites, trachytes and rhyolites) with many pyroclastic flows (that deposited ignimbrites). In central Gran Canaria, Tejeda caldera and a cone sheet swarm were formed in this phase. From 8.5 to 5.3 Ma, in the erosional stage, there was minimal volcanic activity. Erosion occurred along with deposition of alluvial sediments on the island and deposition of submarine turbidite sediments offshore. cover an area of of the Maspalomas cuspate foreland on Gran Canaria's south coast. Aeolian landforms found in this dune field include barchan dunes and dune ridges (transverse dunes). The dunes are made of sand grains and pebbles. The average thickness of the dunes is but some dunes reach thick. In a few areas, the underlying deltaic sediments are exposed. The sand that has built the dunes has been moved about by water waves and wind from the sediment source area (an offshore submarine shelf at Playa del Inglés). Since the 1960s, urbanisation has affected the local winds and this has caused the gradual reduction in volume and area of the dune field because sediment erosion now exceeds sediment deposition. A 2008 study, however, found evidence supporting a hypothesis that the dunes formed less than 300 years ago, as a consequence of a tsunami generated by the 1755 Lisbon earthquake. ==Tenerife==

Tenerife's subaerial shield stage of island development started at about 11.9 Ma in the late Miocene Epoch. First, a shield volcano called Tenerife central shield volcano grew as an island at what is now the central part of Tenerife. This central shield volcano was active from 11.9 to 8.9 Ma. The rejuvenation stage of Tenerife (after a long erosive gap in activity at the centre of Tenerife) started at about 4 Ma and continues to the present day. Between 4.0 and 0.2 Ma, a large stratovolcano (Las Cañadas volcano) formed, centred in the central part of Tenerife. Las Cañadas volcano covered some parts of the three older shield volcanoes. This volcanic activity at the centre of Tenerife has included cycles of basaltic lavas (e.g. basanites and tephrites) alternating with significant amounts of magmatically differentiated (more felsic and more alkaline) lavas (e.g. tephri-phonolites and phonolites). Central volcanic activity has been accompanied, since 3 Ma, by mostly basaltic fissure eruptions at a three-armed Y-shaped radial rift zone system that has northwest, northeast and south rift zones. In eastern Tenerife, large landslides on the flanks of the ridge (known locally as Cumbre Dorsal) that marks the northeast rift zone, formed Güímar valley sometime between 850,000 and 570,000 years ago, La Orotava valley sometime between 570,000 and 540,000 years ago, and another valley less than 560,000 years ago. The nature of this collapse has been studied by many geologists during the last two centuries. Suggested causes of Las Cañadas volcano's collapse are landslide (the Icod landslide), or explosive volcanic eruption, or a combination of both. Most of Tenerife's Holocene eruptions have occurred at the radial rift zones rather than at the two stratovolcanoes. During the Holocene Epoch, Tenerife has had 42 confirmed volcanic eruptions, which is more than any other Canary island. The most recent eruption of lava at Teide's summit vent occurred 1,150 years Before Present. The latest eruption of Pico Viejo is the Chahorra flank eruption of 1798. The most recent eruption in the northeast rift zone is the 1704–1705 eruption at Siete Fuentes/Volcán de Fasnia/Las Arenas. The most recent volcanic activity at the northwest rift zone has been the Boca Cangrejo (1492), Garachico/Boca Negra (1706) and Chinyero (1909) eruptions. Measured from the ocean floor, the total height of Tenerife's edifice is 7,500 m (3,715 m above sea level), making it one of the tallest volcanic edifices on Earth (some volcanic edifices in Hawaii are taller). Tenerife is currently at the point in its geological development where the effects of constructive volcanic eruption and destructive erosion are roughly balanced. ==La Gomera==

on the south coast of La Gomera where a cliff exposes Lower Pliocene dark-coloured lava flows (cliff height: approximately ) The seamount base (also known as the Submarine Edifice) of La Gomera was built by volcanic eruptions during the Miocene Epoch. The precise age range of this submarine volcanic activity is uncertain. Dating done in the early 1970s suggested that submarine volcanic eruptions occurred from 20 Ma to 15 Ma, followed by an erosion gap of 5 million years. The reliability of these dates has been questioned; dating done in the 2000s suggests that submarine volcanic eruptions began instead at about 12 Ma. At the end of the seamount stage, the seamount was uplifted and its top surface was eroded. , a Pliocene lava dome on La Gomera In the late Miocene, at about 11 Ma, La Gomera's shield-building stage began. The oldest subaerially-erupted lavas on La Gomera have been dated to 9.4 Ma. From 7.5 Ma to 6.5 Ma, the Vallehermoso stratovolcano grew on top of the partially collapsed shield volcano by eruption of relatively felsic lavas (phonolites and trachytes) which covered much of the older shield volcano. In the early Pliocene, from 5.5 Ma to 4.2 Ma, basaltic lavas were erupted from highland volcanic vents; these lavas flowed over much of the island. For the last 4 million years, there have been no significant volcanic eruptions on the island and La Gomera has been in the erosional stage of its development. (The island's most recent volcanic eruption was a minor monogenetic eruption at Barranco del Machal, during the Early Pleistocene, about 1.94 Ma). and exposed the deeper parts of the volcanic edifices, revealing volcanic plugs, dykes, cone sheets, and lower lava flows. ==La Palma==

of the Basal Complex in Barranco de las Angustias, La Palma La Palma's submarine seamount formed from 4 Ma to 3 Ma, in the Pliocene Epoch. The seamount stage rocks are layers of basaltic to trachytic pillow lavas with hyaloclastites and pillow breccias. Small remnants of the seamount stage rocks are now exposed on La Palma as its "Basal Complex", for example in Barranco de las Angustias. La Palma's shield-building stage began at 1.77 Ma - the Garafía shield volcano grew, on top of the seamount, between 1.77 Ma and 1.20 Ma (forming the present-day northern part of La Palma), with the oldest subaerial lavas dated to 1.7 Ma. This shield volcano grew quickly to a height of about and a diameter of about but this volcano became unstable and its southern flank collapsed in a large landslide at 1.2 Ma. Only a small part of Garafía shield volcano is visible now because much has been eroded away or is buried by younger lavas. After the Garafía landslide, the focus of volcanic activity moved slightly to the south, producing another shield volcano, named Taburiente volcano, on top of Garafía shield volcano's collapsed southern flank. exposed in the northern cliff of Caldera de Taburiente at Roque de los Muchachos, La Palma (scale: approximately across) For most of its active period, Taburiente shield volcano erupted basaltic lavas but final phases of its formation included phonolitic and trachytic lavas. Together, the three successive, superimposed shield volcanoes (the seamount, Garafía and Taburiente) form the Northern Shield. A three-armed Y-shaped volcanic rift system developed at Taburiente volcano; this northern La Palma rift system had three radial arms - northwest, northeast and south - meeting at the shield volcano's summit. Gradually, most of Taburiente's volcanic activity became focused on the south rift. Cumbre Nueva had a period of particularly rapid growth from 621,000 to 566,000 years ago. (middle and foreground), looking north from Deseada, La Palma Taburiente volcano grew to an estimated maximum height of about resulting in the formation of a large crater named Caldera de Taburiente; it is an erosion caldera formed by mass wasting, not a collapse caldera formed by volcanic eruption. The Caldera de Taburiente is a topographic depression; from the time of the landslide until the present day, it has been enlarged by erosion and is now long, wide and deep. Also after the landslide, Cumbre Nueva grew rapidly again until about 490,000 years ago. Volcanic activity then appears to have paused for the next 275,000 years. About 125,000 years ago, the focus of volcanic activity moved south again, with eruptions of mostly mafic alkaline lavas gradually forming Cumbre Vieja, a ridge-shaped elevated rift zone volcano that has grown until the present day at southern La Palma's north–south volcanic rift zone. Cumbre Vieja reaches in height and it dominates the geology of the southern half of the island. These historical eruptions have mostly been of the strombolian type, forming cinder cones; magmas have been predominantly mafic in composition but some more felsic phonolites have also been produced. Day et al. (1999) led them to suggest that if a large landslide of Cumbre Vieja's volcanic rocks were to occur in the next few thousand years, it could displace a large volume of ocean water that would cause widespread tsunami damage along Atlantic Ocean coastlines. This suggestion has been opposed by some geologists who assess southern La Palma's volcanic rift zone to be stable and any generated tsunami would be much smaller than Ward and Day's modelled size, suggesting that Cumbre Vieja's collapse and damage scenarios would be less severe than Ward, Day and some popular science television documentaries have claimed. (See also: Cumbre Vieja tsunami hazard and Megatsunami). ==El Hierro==

El Hierro is the youngest and smallest of the seven main Canary Islands. During the Early Pleistocene, a submarine seamount grew upwards from the ocean floor, almost to sea level, on top of Cretaceous-Pliocene oceanic sediments. Then, at 1.2 Ma, Tiñor shield volcano began to form on top of the seamount. Tiñor volcano's first subaerial lava was erupted at 1.12 Ma. Tiñor grew by erupting lavas across what is now the eastern half of El Hierro until about 882,000 years ago; the eruptions were mostly of effusive basaltic lava, but there was also an explosive, xenolith-rich last eruptive phase (the Ventejís volcanics). This left a curved bay where the volcano's flank had been. About 545,000 years ago, El Hierro's second subaerial shield volcano, named El Golfo volcano (also known as the El Golfo-Las Playas Edifice), started erupting. Its summit was slightly to the west of Tiñor volcano. Lavas from El Golfo volcano filled the bay that had been formed by the Tiñor landslide. El Golfo volcano's later lava flows covered the remains of Tiñor volcano. At its maximum development, El Golfo volcano was about high and about in diameter, with a surface area slightly larger than present-day El Hierro and about twice the area that Tiñor volcano had covered. • the El Julán lateral collapse, in which much of the southwest flank of El Golfo volcano slid downwards and onto the ocean floor, occurred at least 158,000 years ago; This landslide formed the curved El Golfo bay and a curved landslide scar depression, where the volcano's flank had been; the bay still forms the curved northwest coast of El Hierro. The El Golfo landslide scarp is preserved today as a cliff with a maximum height of ; the cliff is roughly parallel to the coast but about inland, except at each end, where the cliff meets the coast. The age of the El Golfo lateral collapse landslide is poorly constrained; it occurred sometime between 133,000 and 13,000 years ago. This removal of lava has hindered efforts to estimate El Hierro's magma production and eruption rates. Of the volcanic eruptions on land at El Hierro that have been dated, the two most recent were at 2,500 years ago (at Montaña Chamuscada), and 2,280 years ago (at Montaña Los Cascajos), both located on the north-north-east rift. In 2011, a period of seismic unrest (associated with underground movements of molten magma) was followed by El Hierro's most recent volcanic eruption, which occurred underwater on the volcanic rift about south of the southern tip of the island. Initially, this volcanic edifice was at a depth of , but by the end of the eruption, the edifice had grown to below sea level. ==Possible future islands==

One or more of the seamounts in the western part of the Canary Volcanic Province may erupt enough lava to form new islands in the future. For example, El Hijo de Tenerife is a seamount on the ocean floor between Gran Canaria and Tenerife. It is about 200,000 years old and it is thought that it may form a new island within the next 500,000 years. This seamount is in one of the most seismically active parts of the Canary Islands region. A group of three seamounts called Las Hijas (Spanish for 'The Daughters') are located on the ocean floor southwest of El Hierro. These seamounts were surveyed by side-scan sonar in 1997 and were assumed to be less than about 500,000 years old and, therefore, were suggested as candidates for eventually becoming new islands. However, later dating of rock samples from Las Hijas has yielded ages of about 141 Ma, which would make Las Hijas probably the oldest seamounts in the Atlantic Ocean. This old age prompted an alternative name to be suggested: 'Bisabuelas' (Spanish for 'Great-grandmothers'). ==Volcanic landforms==

The Canary Islands have examples of many types of volcanic landforms. Some examples are listed in the following table: ==Geological hazards==

Volcanic hazards and risk Volcanic hazard is the probability of damaging physical phenomena, produced by a volcano, occurring in a particular area during a particular time interval. The closely associated concept of volcanic risk is an estimate of the human, infrastructural, and other costs and impacts resulting from the occurrence of volcanic hazard, measured against how such impacts may be mitigated.) lives less than from an active volcano. The islands are also visited by many tourists (17.77 million in 2024). Potential volcanic hazards in the Canary Islands include lava flows, pyroclastic flows and pyroclastic falls, volcanic gas emissions, lahars, and edifice collapses. Unlike some other ocean island chains (e.g. the Hawaiian Islands) where active volcanoes are confined to one end of the chain, the active volcanoes of the Canary Islands are located along the entire length of the chain. This wide spatial spread of eruptions makes it more difficult to predict which Canarian island will have the next volcanic eruption. During historical volcanic eruptions on the Canary Islands, lava flows have not endangered human life directly, but they have destroyed thousands of buildings and destructively covered agricultural land, forestry areas, and roads in the Canary Islands. Pyroclastic airfall material (tephra), including volcanic ash, has also damaged buildings by roof collapse due to excessive ash accumulation on roofs. In the last 158,000 years, the most common type of volcanic eruption on El Hierro has been mafic strombolian eruptions at monogenetic vents. This is expected to also be El Hierro's most likely type of volcanic activity in the geologically near future. Scientists have concluded that future volcanic eruptions are more likely to occur at the western islands (Tenerife, La Palma, El Hierro). Volcanic hazard and risk assessments have been done for the islands. These assessments have involved study and mapping of volcanic eruption products produced during past eruptions, which give indications of the location, frequency, severity, and probability of eruptions. The completeness of this information varies among the islands. This information has been input into geological computer modelling of hazard and risk for various future volcanic eruption scenarios. Due to the incompleteness of the record of past eruptions, there is considerable uncertainty in the hazard and risk assessments for most of the Canary Islands. The record of past eruptions is better known on Tenerife and La Palma; scientists therefore have more confidence in the accuracy of the hazard and risk assessments for these islands. La Palma and Tenerife have been assessed as the two Canarian islands facing the greatest volcanic hazards. These two indices combine to give Tenerife and La Palma a risk level of II (from a possible range of I, II or III). where volcanic risk coefficient = log(1/years since last eruption) + maximum expected volcanic explosivity index + log(human population). The first local seismometer measurements of earthquakes in the Canary Islands were made in 1891 but it was not until 1952 that the first permanent Canarian earthquake monitoring station was established at Santa Cruz on Tenerife. 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33 km ESE of Fasnia, Spain" }, "geometry": { "type": "Point", "coordinates": [-16.156, 28.071, 23.3] }, "id": "usp0003v2e" } ], "bbox": [-18.2868, 27.548, 7.48, -14.56, 28.978, 59.9] } The seismicity of the Canary Islands is very low to low. The USGS Earthquake Catalog reports that from 1 January 1976 to 31 December 2024, 17 earthquakes of magnitude 4.0 or larger, with epicentres on or close to the Canary Islands, were recorded; the largest of these earthquakes had a mb magnitude of 5.4 and an intensity of VII with its epicentre on the ocean floor about west of El Hierro in 2013. Periods of increased seismic unrest occurred on Tenerife in 2004–2005 and 2016–2021. In 2004–2005, an earthquake swarm of about 200 earthquakes occurred along the northwest rift zone of Tenerife. The swarm was probably caused by a movement of molten magma and associated magmatic gases disturbing Teide's hydrothermal system. During the eruption, larger earthquakes were detected, for example an earthquake of mbLg magnitude 4.3 occurred below the surface. In the last 500 years, at least four tsunamis that were triggered by distant earthquakes, have hit the coasts of the Canary Islands. They occurred in 1755 (1755 Lisbon earthquake), 1761 (1761 Lisbon earthquake), 1941 (1941 Gloria Fault earthquake) and 1969. ==Geological resources==

Onshore Volcanic rock has been extracted at quarries scattered across the Canary Islands. This includes at some volcanic cones, for example Montaña de El Palmar in northwest Tenerife, where basaltic lapilli tephra (known locally as "picón") has been removed for use as horticultural substrate and road construction aggregate. Phonolitic and trachytic pyroclastic rocks (including pumice) of intermediate composition have been used as a building material. For example, Bandas del Sur ignimbrite of the Poris Formation has been extracted from quarries at Tajao and at Poris de Abona in southern Tenerife. Similar pyroclastic rock has been extracted from quarries on Gran Canaria and Fuerteventura. Starting in the first half of the 16th century, on Tenerife, sulfur was extracted from fumarolic areas at Teide's summit. Initially, the extracted sulfur was used as an ingredient in gunpowder. Later, sulfur was used by local farmers to protect their grape crop against diseases. Extraction of sulfur at the volcano continued until the 1940s. The sedimentary rock calcrete (also known as caliche) was extracted at some quarries in southwestern Gran Canaria, then heated in kilns to produce lime for use in construction. Calrete extraction for lime production also occurred on Fuerteventura. Deposits of some rare-earth elements have been found in two settings in the Canary Islands: (1) pegmatitic syenites of southwest Tenerife and northeast La Gomera; (2) carbonatites in the Basal Complex of northwest and central Fuerteventura. The potential exploitation of shallow high-enthalpy geothermal energy resources has been investigated on Lanzarote, Tenerife and La Palma. The geothermal energy originates from hot volcanic sources in the bedrock. A crater rim surface temperature of , as well as a borehole temperature of at a depth of , have been recorded at Timanfaya, Lanzarote. High-enthalpy geothermal energy has been used to heat the water supply of a winery on Lanzarote using a borehole heat exchanger field of twelve boreholes, as part of the Shallow Geothermal Energy for the Canary Islands (SAGE4CAN) project. , an experimental project on Lanzarote has been investigating the generation of electricity using the hot dry rock heat source provided by the island's geologically recent volcanic activity at Timanfaya, where installed thermoelectric generators are capable of producing 4.4 MWh of electricity per year. Reservoirs for fresh water have been built in the craters of some volcanic cones, e.g. Laguna de Barlovento (in northeast La Palma) and Montaña de Taco (in northwest Tenerife). Geotourism lava tube on Lanzarote in 2022 The geological features and landscapes of the Canary Islands are sites of geotourism. Many features and sites are protected in a network of national parks, natural parks, rural parks, natural reserves, natural monuments, and sites of scientific interest. Examples are: TFGeoturismo is a local government project promoting geotourism in Tenerife. It began in 2017 and is supported by the Cabildo (Island Council) of Tenerife and operated by INVOLCAN, the organisation that oversees various aspects of volcano–human interaction in the Canary Islands. Teide National Park is particularly significant in Tenerife's geotourism strategy because it provides a high-profile opportunity to improve public awareness of Tenerife's volcanic heritage; it is Spain's most visited national park and one of the world's most visited volcanic areas. (In 2016, 2017 and 2018, Teide National Park had more than 4 million visitors per year). TFGeoturismo has promoted Teide National Park by making and screening a documentary film about the park, as well as publishing a guidebook describing and explaining the park's geology, geomorphology and volcano-related natural and cultural heritage. The project has also published a set of urban geotourism guide leaflets for more than 20 municipalities of Tenerife, e.g. Garachico. TFGeoturismo has published a guide promoting the role of Tenerife in the history of science, describing 18 locations along the route of Alexander von Humboldt's 1799 journey from Puerto de la Cruz to the summit of Teide. Even before tourism became a major part of La Palma's economy, some tourists were attracted to the island due to the 1949 and 1971 volcanic eruptions. Although the 2021 eruption had numerous negative effects for La Palma's resident population, tourists who wanted to see a volcanic eruption visited the island. A survey of 1,026 people who visited La Palma during the 2021 eruption indicated that most of the tourists came from the other Canarian islands and that the erupting volcano had become the island's main tourist attraction, with 64.3% of survey respondents stating that their reason for visiting La Palma was to witness the volcanic eruption. Exploration of these resources is underway. , one offshore well (Sandia-1) had found petroleum in Tertiary-age sandstone. , two offshore exploration wells had found heavy oil but they are not commercially viable. ==Gallery==

File:Paisaje lunar Los Escurriales.jpg|Pillars ("fairy chimneys") of Lower Pleistocene pyroclastic rock at Los Escurriales/Paisaje lunar, near Vilaflor, Tenerife File:Detail to cinder particles forming flanks of cone Caldera de los Cuervos on Lanzarote, June 2013(2).jpg|Cinders of the cone of Caldera de los Cuervos on Lanzarote, with camera lens cap ( across) for scale File:Volcanic Cones and Pahoehoe Lava at La Restinga El Hierro.jpg|Volcanic cones and pahoehoe lava at La Restinga on El Hierro File:At Tenerife 2022 019.jpg|Pyroclastic layers (light-coloured phonolitic pumice and dark-coloured basaltic lapilli) at Curvas del Pastel/La Tarta del Teide on Tenerife (scale: cliff height is approximately ) File:Roque de Taborno - Tenerife 03.jpg|Basaltic lava flows and subordinate pyroclastic rock layers cut by vertical dykes at Roque de Taborno in the Anaga Massif on Tenerife File:Interesting Rocks 2 (2282500010).jpg|Hydrothermally-altered Miocene intra-caldera tuff layers at Fuente de los Azulejos near Tasarte, Gran Canaria File:Caleta Negra - Ajuy - cropped.jpg|Cliff at Caleta Negra, Ajuy on Fuerteventura. The lower third of the cliff consists of steeply-tilted pre-Miocene oceanic sedimentary rocks. These rocks are unconformably overlain by Pliocene light-coloured cross-bedded beach sedimentary rocks, black pillow lava, and a black lava flow. (Scale: cliff height is approximately ) ==See also==