Geology of the Canary Islands

The geology of the Canary Islands is shaped by volcanoes and volcanic rock. The Canary Islands are a group of islands in the North Atlantic Ocean, close to the coast of Northwest Africa. These islands include Lanzarote, Fuerteventura, Gran Canaria, Tenerife, La Gomera, La Palma, and El Hierro, along with smaller islands and islets.

The islands sit on the African tectonic plate, far from where the plate edges meet. This distance influences the type of volcanic activity, called intraplate volcanism, that created the islands. The Canary Islands are part of the Canary Volcanic Province, which has seen volcanic activity for about 70 million years. For many years, all the eruptions happened deep underwater. Over the past 20.2 million years, enough lava built up to create islands above sea level. The eastern islands appeared first, followed by those farther west.

Volcanic activity has continued into recent times, during the Holocene Epoch, the last 11,700 years, on all main islands except La Gomera. The area remains volcanically active. The last eruption on land happened in 2021, and the most recent underwater eruption was between 2011–2012.

Islands

The Canary Islands are a group of islands that stretch 450 km (280 mi) from east to west in the North Atlantic Ocean. They sit about 100 to 500 km (60 to 310 mi) off the coast of Northwest Africa. There are seven main islands, from east to west: Lanzarote, Fuerteventura, Gran Canaria, Tenerife, La Gomera, La Palma, and El Hierro.

Close to the shores of these islands are smaller islands and tiny rocks. Near Lanzarote are places like La Graciosa and Alegranza. Near Fuerteventura is Lobos. Near Tenerife are Roques de Anaga and Roque de Garachico. Each of the larger islands also has a few small nearby rocks.

All of the Canary Islands began as underwater volcanoes on the deep ocean floor. Over time, layers of volcanic rock built them up so they rose above the water.

Regional setting

The Canary Islands are built on very old parts of the ocean floor. These parts belong to the African plate near Northwest Africa.

The rocks beneath the Canary Islands show many periods of volcanic activity. About 180 million years ago, the floor of the North Atlantic Ocean formed. This happened because the continents moved apart, making new ocean floor. Later, around 70 million years ago, volcanic activity made many underwater mountains, called seamounts, where the Canary Islands now are. Some of these seamounts grew tall enough to become islands. The Canary Islands themselves emerged between about 20 million and 1 million years ago. Volcanic activity in this area continues today.

Island development stages

See also: Evolution of Hawaiian volcanoes

The Canary Islands are special because they formed far out in the deep ocean, away from places where Earth's plates push together. They are different from the Hawaiian Islands.

These islands grow in steps. First, they form under the water as mountains. Then, they grow bigger with lava until they break the surface and become islands. After that, they may wear down from weather and waves. Finally, some can grow active again and build up once more. Each of the Canary Islands is at a different step in this journey, which is why some are tall and rugged, while others are lower and smoother.

Age

The Canary Islands were made by underwater volcanic eruptions that started about 70 million years ago. Over time, lava built up and created the islands we see today. Each island began forming at different times. The eastern islands such as Lanzarote and Fuerteventura formed earlier than the western islands like La Palma and El Hierro. This shows that the islands grew from east to west over millions of years.

Geological map

The map shows the geology of the Canary Islands. The islands are made of volcanoes and volcanic rock. You can see different types of volcanic activity, like recent eruptions and older areas from millions of years ago. The islands are in the Atlantic Ocean, near Africa.

Rock types

Igneous rocks

The Canary Islands have many types of igneous rocks, especially from the alkaline magma series. Rocks from the sub-alkaline tholeiitic magma series are less common.

You can find many volcanic rocks here, such as alkali basalts, basanites, phonolites, trachytes, nephelinites, trachyandesites, tephrites, and rhyolites. There are also lava flows and deposits of pyroclastic material like tuff, made from volcanic ash or lapilli.

Some plutonic rocks, like syenites, gabbros, and pyroxenites, appear on Fuerteventura, La Gomera, and La Palma. These formed deep below the surface.

Fuerteventura is special because it has carbonatite rocks, which are igneous intrusions. Apart from some islands in Cape Verde, it is the only place where these rocks are found.

Sedimentary rocks

There are small amounts of sedimentary rocks on the Canary Islands. These include calcrete/caliche, sandstone, conglomerate, aeolianite, and limestone.

Metamorphic rocks

Some metamorphic rocks can be found on the Canary Islands.

The oldest parts of Fuerteventura, La Gomera, and La Palma have rocks that were changed by heat and pressure. These rocks were folded before the islands rose above the water.

Small amounts of migmatite and hornfels are found near igneous intrusions in Fuerteventura.

In Lanzarote, some sedimentary rocks were changed by heat from magma. Sandstones turned into quartzite, and shales became slate. Later volcanic activity brought pieces of these rocks to the surface within basaltic lava.

Origins of volcanism

Scientists have many ideas about why the Canary Islands are made of volcanoes. Two main ideas are popular:

1. The volcanoes might be linked to cracks in the Earth’s surface coming from the Atlas Mountains in Morocco.
2. Another idea is that the African plate is slowly moving over a special spot deep inside the Earth called a hotspot.

Most experts today think the hotspot idea makes the most sense. They believe a column of hot rock rises from deep below the island of La Palma and El Hierro. This helps explain patterns in the ages of rocks on the islands.

Volcanic eruption distribution

The Canary Islands have had many volcanic eruptions over thousands of years. There have been seventy-five known eruptions, fifteen of which happened after the year 1490 and have written records. On average, a volcanic eruption happens somewhere in the Canary Islands every 30 to 35 years. But the time between eruptions can change a lot on each island. For example, La Palma has had eruptions from 26 to 237 years apart, and Tenerife from 1 to 212 years apart.

One big eruption happened about 2,000 years ago on Tenerife. The longest and largest eruption with written records was in the early 1700s on Lanzarote.

Tenerife and La Palma comparison

Over the last 10,000 years, Tenerife and La Palma have been the most active volcanic islands in the Canary Islands. The chart below shows how many eruptions happened on each island during different time periods.

Lanzarote

Lanzarote is a volcanic island that started forming about 28 million years ago. First, underwater volcanoes built up a mountain from the deep ocean floor. Later, above-water volcanoes grew and made two main islands that joined together to become Lanzarote. Over millions of years, the island changed shape with volcanic activity and erosion.

About 2.7 million years ago, new volcanoes began erupting again. More recent eruptions happened at Montaña Corona around 21,000 years ago, Timanfaya between 1730 and 1736, and Tao/Nuevo del Fuego/Tinguatón in 1824. The Timanfaya eruption was very big and covered a large part of the island with lava.

Fuerteventura

Fuerteventura is the closest of the Canary Islands to Africa, about 70 km from the edge of the African continental shelf.

The island has two main types of rock layers. The older layer, from the Cretaceous to early Miocene, includes rocks formed underwater. Over this is a younger layer of volcanic rocks from the Miocene to Quaternary.

Fuerteventura has the oldest known above-ground volcanic rocks in the Canary Islands, from about 20.2 million years ago. These rocks came from three large shield volcanoes.

Gran Canaria

Gran Canaria is a volcanic island that formed in three main steps. First, underwater volcanoes made a large landmass long ago. Later, the land wore down, and sand and mud gathered around the island. Finally, volcanoes became active again, forming famous places like Roque Nublo. The last eruption happened about 2,000 years ago near Bandama crater.

On the south coast of Gran Canaria, there is a big area of sand dunes at Maspalomas. These dunes were made by wind and water, and they have changed over time because of buildings and natural events. Some scientists think the dunes formed recently after a big ocean wave in the 1700s.

Tenerife

Tenerife is a volcanic island that started forming about 11.9 million years ago. It began with three big shield volcanoes: the central shield, Teno in the northwest, and Anaga in the northeast. These volcanoes helped shape the island.

Later, a big volcano called Las Cañadas formed in the middle. It erupted many types of lava and created a rift zone with three arms. Over time, part of this volcano fell down, making a large valley called Las Cañadas caldera. Inside this valley, two smaller volcanoes grew: Teide and Pico Viejo. Both are still active today.

Tenerife has had more volcanic eruptions than any other Canary island in the last few thousand years. The last big eruption was in 1798, and smaller eruptions happened as recently as 1909. From the ocean floor to the top of Teide, Tenerife rises about 7,500 meters, making it one of Earth's tallest volcanic structures.

La Gomera

La Gomera is a volcanic island. It formed from underwater eruptions millions of years ago. Scientists think these eruptions began about 12 million years ago. After the eruptions stopped, the island rose above the water and began to wear down.

Later, around 11 million years ago, a big shield volcano started to form on La Gomera. This volcano grew for about a million years before part of it fell down. After that, a new volcano called Vallehermoso formed on top of the old one. Over time, more lava flows covered much of the island. For the past 4 million years, La Gomera has not had any big volcanic eruptions. It has been shaped mainly by erosion. Some scientists think La Gomera might no longer be active, but others believe volcanic activity could return in the future.

La Palma

La Palma is a volcanic island made from layers of lava and volcanic rocks. It has three big shield volcanoes that grew over time. The oldest part of the island is called the "Basal Complex," and you can still see it in some places today.

The biggest volcano on La Palma is called Taburiente. It grew very tall but later fell down in a big landslide. After that, a new volcano called Cumbre Vieja formed. Cumbre Vieja has been active in recent times, with its last eruptions in 1949, 1971, and 2021.

Cumbre Vieja is still active today. Some scientists think a future landslide might create a big wave in the ocean, but others think this risk is not as big as some people say.

El Hierro

El Hierro is the youngest and smallest of the seven main Canary Islands. It is still growing through volcanic activity.

Long ago, underwater mountains rose up from the ocean floor near where El Hierro is today. Over time, volcanoes began to build up above the water. The first big volcano, called Tiñor, started growing about 1.2 million years ago. It erupted lava that helped shape the eastern part of the island. Later, around 545,000 years ago, another volcano named El Golfo began to form. This volcano grew very large and helped give El Hierro its round shape.

Today, El Hierro is still active with many small volcanoes along three main lines that stretch from the center of the island out to the ocean. These lines are called rift zones. In recent years, there have been many small eruptions on land. The most recent big eruption happened underwater near the island in 2011 and 2012. Lava flowed from a vent under the sea, creating a new underwater mountain.

Possible future islands

Some underwater mountains, called seamounts, near the Canary Islands might one day grow big enough to become new islands. One of these is called El Hijo de Tenerife, located between Gran Canaria and Tenerife. It is thought that this seamount could rise above the ocean in the very far future.

Another group of seamounts named Las Hijas is found far to the southwest of El Hierro. Scientists first thought these might become islands, but later discovered they are very old, much older than originally believed.

Volcanic landforms

The Canary Islands have many shapes made by volcanoes. These shapes are called volcanic landforms. Some examples are in the table below:

Geological hazards

Volcanic hazards and risk

Volcanic hazards are events from volcanoes that can harm people and places. The Canary Islands have many active volcanoes, and millions of people live or visit these islands. Possible dangers include lava flows, fast-moving rocks and ash, volcanic gases, and the collapse of volcanic structures.

Unlike some other island groups, the active volcanoes on the Canary Islands are spread out, making it hard to know which island might erupt next. In the past, lava flows have damaged buildings and land but not hurt people directly. Ash from eruptions can also damage roofs and make cleaning harder.

Scientists study past eruptions to understand future risks. They use computers to model where and how eruptions might happen. However, because we don’t have full records of all past eruptions, there is some uncertainty about future risks.

Earthquakes

Earthquakes near the Canary Islands are usually linked to movements of underground magma or the shifting of the Earth’s crust. The islands have a good network of earthquake monitoring stations, which helps scientists track these events.

Most earthquakes in the region are small, but some have been strong enough to feel. In recent years, periods of increased earthquake activity have been observed, sometimes before volcanic eruptions. These swarms of earthquakes often happen as magma moves underground.

In the past 500 years, a few tsunamis caused by faraway earthquakes have reached the Canary Islands.

Geological resources

Volcanic rock has been taken from places across the Canary Islands. At Montaña de El Palmar in northwest Tenerife, a special type of rock called "picón" has been used for gardening and building roads.

Other rocks, like pumice, have been used as building materials. On Gran Canaria and Fuerteventura, lapilli has been used in heat exchangers and filters. In the past, sulfur was taken from Tenerife and used for making gunpowder and protecting crops.

The Canary Islands also have places where special elements and geothermal energy can be found. On Lanzarote, hot water from underground has been used to heat a winery. Some craters have been turned into reservoirs for fresh water.

The islands' unique landscapes attract visitors interested in geology. Teide National Park on Tenerife is very popular, and there are many protected areas for people to explore. Projects help share the islands' volcanic history with visitors.

The ocean near the islands may hold oil, but finding and using it is still being studied.