It is sometimes said to be the highest volcano in Europe. There is an obvious problem with that: El Teide is not in Europe. It may be Spanish, but the location is in the Canary Island which politically are included in Europe but geographically are not. A second problem is that there are much higher volcanoes in the Europe, in the Caucasus, but let’s not mention that.

By another measure, Teide is considered the 3^rd tallest volcano in the world. This is measured from the sea floor on which it rests, which makes it 7.5 km tall. It certainly sounds impressive. From land, the volcano looks funny. It has an impressive edifice which dominates Tenerife and makes driving up the steep sides an interesting experience. Living on the edge is also not for everyone. But at the summit, the mountain becomes a cone which seems far too small in comparison to the giant edifice.

Teide is the main mountain of Tenerife, the largest island of the Canary Islands, off the coast of Morocco. Before the Spanish colonization, it was inhabited by people known as Guanches (literally ‘people of Tenerife’), originating from northwest Africa and related to the Berber people. When they arrived is not known, but the oldest archaeological sites are dated between 600 and 500 BC. One suggestion is that they came because of the desertification of the Sahara, but this could still be anywhere between 6000 and 1000 BC.

The Canary Islands were well known during Roman times but Roman records suggest the population in those times was sparse. However, archaeological remains of the Gaunchos culture are found across the archipelago. Little else remains, though. The people were largely (or completely) wiped out during the Spanish conquest. Fragments of their language survived, and we know of some of their belief systems. Teide was considered the domain of an evil demon, Guayota. A story quoted on the national park website relates that “Guayota kidnapped the god of the Sun, plunging the island into darkness until Achamán, the supreme sky god, managed to defeat him and free the Sun, sealing the volcano’s mouth with Guayota inside.” (https://www.globalnationalparks.com/spain/teide/) I do not know the origin of this story, but it clearly is based on some significant eruption. Teide is not dead.

The island

Tenerife has the shape of a slightly bent triangle. The tourists are found mainly on the western and southern side, which are the sunniest but far from the prettiest: it is semi-desert, bordering on full desert. The main town on Tenerife is Santa Cruz de Tenerife in the north, and the nicest town to visit is probably Puerto de la Cruz. Teide dominates the southwestern half of the island. A ridge extends from Teide to the northeast, along the Monte de la Esperanza, following an ancient fissure. The northeast tip consists of the Anaga mountains. These mountains are among the oldest part of Tenerife; they formed some 7 million years ago. The Teno mountains at the western tip are of similar age: they form the famous cliffs of the giants along the coast. A third ancient mountain from this era is at Adeje, near the southernmost tip of Tenerife.

At the time, these were three separate islands. They came together 3 million years ago with the growth of Las Canadas at the centre. Las Canadas went through ups and downs, including a giant collapse which formed the Las Canadas caldera surrounding the summit of Teide, around 200,000 years ago. Similar to what is commonly seen in Hawaiian volcanoes, three fissure rifts extended from Las Canadas. One of these formed the dorsal ridge of the Monte de la Esperanza, pointing towards Anaga, and the other two went towards Teno and Adeje. Thus, the three ridges connected the central volcano to the outlying islands.

The current Teide volcano developed after the latest collapse. The 220-meter tall cone on top of Teide formed some 3000 years ago. A satellite cone to Teide is located west of the summit and is called Pico Viejo.

Teide earthquakes

Teide has recently drawn attention because increasing earthquake activity. Not all quaking comes from Teide itself. On February 26, 2026, an earthquake of magnitude 4 hit, strong enough to rattle tourists, but it came not from Teide but from the Enmedio volcano. If that is one you have never heard of, it is 500 meter tall and it located on the seabed halfway to the neighbouring island of Gran Canarias. In 1989 there was an M5 earthquake in the same area.

The proper Teide earthquakes came in two forms. One is that of isolated, weak activity around 10 km below Teide, with locations as in the plot below from March 7. These events have been much too small to be felt.

The other type is in the form of low-frequency earthquake swarms, triggered by ‘fluid pressure’. They have been occurring in the same region in the west of Las Cañadas and at the same depth as the individual events (8-14 km), but consist of thousands of events. The amount of energy in each swarm is small, and adds up to no more than perhaps one M2 earthquake. The swarms are typically associated with migrating ‘fluids’ which could have been magma but in this case appears to be heated water.

The first such swarm occurred on 2 October 2016, almost ten years ago. It consisted of over 700 detected events, and probably many more that could not be separated by the measurements since towards the end of the 5-hour period the swarm became a continuous tremor. One month later, the CO2 emissions from Teide increased. There was no ground inflation. It is plausible the event was related to an overturn in the deep magma system, bringing some hotter magma to the top and triggering a gas escape which slowly made its way to the surface. There were further swarms in later years, most recently in August and November 2024.

But in February this year, the swarms swarmed. There were 7 such swarms in one month, between Feb 6 and 26. A further weak swarm of 90 earthquakes was detected on March 5. The last two events were the weakest, indicating the swarm of swarms is fading.

The most likely cause of the swarming is increased heat entering the magma chamber. There has also been some slow inflation in recent years.

Eruptions

Teide is not very active. It has a relative low eruption frequency, well below that of nearby La Palma. The eruptions also have low explosivity. The last time the summit itself erupted was 1000 years ago. Most eruptions have been around the base of the current Teide volcano, around the rim and edge of Las Canadas caldera. Several such eruptions have been documented since the Spanish conquest. They occurred in 1704-1706, 1798 and 1909.

Little is known about older eruptions. Sailor reports exist (including one by Columbus) but often can be explained by normal summit clouds or forest fires, both of which are far more frequent than eruptions. C-14 dating has shown that the most recent summit eruption occurred between around 650 and 950 AD. Columbus reported an eruption ‘high up’ in 1492. That was probably a true eruption, but not near the summit: it can only be assigned to a lava flow on the west side called the Boca Cangrejo, shown on the map below.

1704-1706

After more than 200 years of dormancy, Teide came back to life on Christmas eve 1704 with notable earthquake activity. It intensified on Dec 27 and 28. There was damage along the northeast rift zone, with buildings collapsing in several towns. The eruption started on December 31 1704 with brief activity at Sieta Fuentes (see the map above). Lava flowed for around 1 km and a small cinder cone formed.

On Jan 6, 1705, a new fissure opened 2 km further northeast. Apparently the magma was pushing along a dike in this direction. Initially this formed some 30 small vents, which eventually merged into two conder cones, now known as Volcán de Fasnia. Lava flows of the individual cones remained short, but eventually one reached 5 km downhill before it stopped. Fasnia ceased erupting on January 14.

But this was not yet the end. On February 2, a new vent opened some 8 km further along the same line. This was at lower altitude of 1500 meter, in the Güímar Valley. It formed Volcán de Arafo, now a 100 meter high cinder cone. The lava flows from this cone were more significant, perhaps aided by the lower altitude. Two flows came close to towns, one of which passed Arafo itself before coming to a stop only 1 km from the coast. The eruption ended on March 27, 1705.

There is a similarity to the recent La Palma eruption, with several vents along the side of the rift zone. The upper vents allow gas to escape, whilst lava mainly opts for the lower vent(s).

But although this was the end of the eruption, it was not the end of the activity. Teide was not yet spent. The northeast rift had not erupted for a long time and perhaps was rather resistant to the magma pressure. It closed too early. Earthquake normally ends once an eruption is in progress and certainly when it has stopped. But this time in Tenerife, it continued throughout the rest of the year and into 1706, with ‘underground rattling’ and ‘shaking buildings’. On the night of May 4, 1706, more than a year after the eruption had stopped, the earthquakes again intensified. But they had been going on for so long that people were not taking it as a warning.

The eruption that started the next day came as a surprise. It was some distance from the previous activity, along the northwest rift, close (6 km) to the town of Garachio. By late afternoon that same day, the lava flows had reached the cliffs above the town and split into several branches. There was damage to the town, but the most important damage was to the harbour. Over the next week it was almost completely filled in by the lava, leaving a cove “impracticable even for small boats’’. This was a disaster: Garachio was the main port for resupply on the way to the Americas. All trade along the route ceased, until a new port was developed which would become the town of Santa Cruz de Tenerife.

At first the lava came from a 500-meter long fissure. On May 12 the eruption focussed on the eastern most point of the fissure and a new lava flow traveled along the edge of the previous ones. This flow reached Garachio on May 13 and covered the centre of the town. After this, the eruption diminished. The end date is not fully certain – perhaps people had more important things to worry about than the state of the eruption. The eruption probably lasted until June and perhaps as late as the middle of the month, or 40 days since the beginning. It left a 115-meter tall cone which is now called Montaña Negra, and a lava flow that covered part of the town and much of the harbour.

But why had the harbour been there? The town had originally been built on a flat area at the coast. It turned out, this area had been created by a lava flow dating from some 10,000 years ago. Teide created the town and harbour – and took it away. Typically volcanic.

1798

Almost a century of quiescence followed. In 1795, earthquakes again were felt. The eruption started June 9, 1798. It lasted more than 3 months. The eruption came from a fissure on Pico Viejo, over a length of 1 km downslope. Although in the southwest slope of the volcano, it appears to be an extension of the northwest rift zone, based on the lava composition. The eruption was strombolian with some more intense explosive events. Ash fell over much of Tenerife, and also on the other Canary Islands. There were three vents. As before, each played a different role. A contemporary account states that the first, upper vent produced fume, the second, middle vent stones and lava and the third, lowest vent only lava.

The lava stayed within the Las Cañadas Caldera, well away from habitation. It covered some 5 km² with a thickness up to 15 meters. The total volume is around 0.03 km³. It ended in October 1798.

1909

The most recent eruption occurred in the early 20^th century. There had been 1.5 year of earthquake activity before the eruption started on November 18, 1909. It happened on the northwest rift zone, but formed an east-west fissure. There were 5 vents but they merged into an 80-meter tall cinder cone called Chinyero. Lava flowed in two branches, reaching a few kilometers in this uninhabited region. This was a tourist eruption: boats took people from Santa Cruz de la Tenerife to Garachio (yes, that one) from where they walked up the mountain to admire the lava flows. (It was not the first tourist eruption: that was Krakatau where people went to Krakatau during the early phases of the eruption, before it became too dangerous.)

The eruption lasted 10 days; the lava covered around 2.5 km².

There has been no further activity since 1909. That is not surprising, seeing that we only have had four eruptions in over 500 years.

Future

What does this mean for the current phase of earthquake swarms? It appears, nothing much. The events were preceded by much stronger earthquake activity, in two cases lasting well over a year. The current events are nowhere near that scale. Even of this develops into something more, we could be decades away before this happens. There will be time to prepare. And we will have to be prepared, because Tenerife is far more developed now. We will have to quickly fly out the tourists – while the new tourists fly in to admire the eruption.

Teide is not yet awake. But it may be dreaming.

Albert, March 2026