Geology
Teide vs Pico Viejo: Two Summits, One Complex
Two peaks of one volcano
The relation between Teide and Pico Viejo is often misunderstood. Look at them from the south, from the road rising past the Parador, and they appear as a double summit. Two sibling cones sharing a broad base. The term that appears on geological maps is the Teide–Pico Viejo complex, a single stratovolcanic system that has built its mass through repeated eruptions from two adjacent vents.
Both peaks sit inside the Las Cañadas caldera, the great collapsed basin that dominates the central highlands of Tenerife. That caldera formed roughly 180,000 years ago, after a giant landslide removed the island’s northern flank. In the hollow left behind, subsequent volcanism began constructing the current central cone, first as smaller vents and eventually as the larger edifice we see today. The Teide–Pico Viejo complex is the latest phase of that construction.
The two vents have behaved differently over time. Teide has focused more of its eruptive energy into building height. A narrow, steep cone that rises into the trade-wind zone and occasionally carries snow into May. Pico Viejo, broader and lower, was the site of the longest and most voluminous effusive eruptions in the complex’s recent history. That difference in eruptive behaviour is the reason Pico Viejo’s crater dwarfs Teide’s.
| Feature | Teide | Pico Viejo |
|---|---|---|
| Elevation | 3,715 m | 3,135 m |
| Summit crater diameter | roughly 80 m | roughly 800 m |
| Alternative name | — | Montaña Chahorra |
| Summit access | Trail 10, permit required | Trail 11 viewpoint, no permit |
| Active fumaroles | Yes, at the summit crater | No |
Why Pico Viejo’s crater is far larger
It seems counterintuitive. A mountain lower by several hundred metres should not carry a crater an order of magnitude wider. The explanation lies in the character of the eruptions that formed them.
Teide’s summit cone was constructed largely by Strombolian activity. Moderate explosions that threw lava bombs and scoria into the air, building a steep cone around a narrow central vent. The resulting crater is roughly 80 m across, a small bowl that sits at the very top of a steep pyramid. Below it, the volcano’s flanks have been shaped by lava flows and minor explosive events that added height more than breadth. The summit fumaroles visible today, faint wisps of steam and volcanic gas rising from rock crevices, are evidence that the throat of Teide’s conduit remains open and active.
Pico Viejo’s crater tells a different story. The summit we see today is not a constructional cone but the remnant of a much larger collapse structure. At some point in the volcano’s development, probably during a phase of significant magma withdrawal, the summit area foundered. This created a broad depression that later eruptions partly filled and partly carved. The result is a crater roughly 800 m across, with an interior whose walls display strong colour banding: yellows, ochres and deep reds from hydrothermal alteration and oxidised scoria. The effect is vivid enough to be visible from the road.
The scale of Pico Viejo’s crater is not a sign of greater violence but of a different style of eruption. Where Teide built upwards with repeated small explosions, Pico Viejo’s largest events involved the collapse of its own summit, widening the crater rather than raising the peak. The 800 m diameter is the footprint of that collapse, not of the cone that preceded it.
The 1798 eruption: Narices del Teide
The most significant historical eruption of the Teide–Pico Viejo complex did not occur at either summit. In June 1798, after several months of seismic activity, a series of vents opened on the southwestern flank of Pico Viejo, at an elevation of roughly 2,700 m. The eruption lasted about three months. The longest historical eruption on Tenerife. It produced a broad field of black lava that remains conspicuously bare today, free of the lichen and soil that cover older flows nearby.
The vents are known as Narices del Teide, “the nostrils of Teide.” A name that captures how the eruption was perceived at the time: as a breathing event from the larger mountain, not an independent act of Pico Viejo. The lava that issued from those vents flowed west, covering the floor of the caldera and piling into the slopes that lead down towards Boca Tauce. It did not threaten any settlement. The area was uninhabited then and remains so now.
What makes the 1798 eruption useful for understanding the complex is its volume. The eruption produced a significant amount of lava for a historical event, but it came from a flank vent, not from Pico Viejo’s summit. The summit crater itself saw no activity. That pattern, long-lived effusive flank eruptions that bypass the main conduit, is typical of this volcanic system and explains much of the difference between the peaks. Teide has produced a narrower, more focused vent system. Pico Viejo has a broader, more diffuse plumbing system that allows magma to escape laterally.
What you see from each summit
Teide’s summit, at 3,715 m, offers the most extreme high-elevation experience in Spain. Reaching it requires a permit. Trail 10 from La Rambleta, the cable car’s upper station at 3,555 m, takes about an hour of careful climbing on steep volcanic gravel. The crater is small and its rim is partly obscured by rockfall and snow. What stands out is the view. To the west, the whole of Pico Viejo and its vast crater appear exactly as the cartographers drew it, a great dish set into a broad shoulder. To the north and east, the island falls away towards the coast, cloud often filling the valleys below. The fumaroles are faint threads of vapour near the crater’s eastern edge, their presence marked by a faint sulphur scent when the wind is right.
Pico Viejo’s viewpoint, reached by Trail 11, requires no permit. The walk from La Rambleta is roughly level and takes about half an hour one way. The crater edge here is the reward. You stand directly above an 800 m depression whose walls show the full colour sequence of volcanic alteration. Black scoria grading through rust red to pale yellow. On a clear morning, with the sun behind you, the banding is sharp enough to read the mineralogical history in the rock. Teide rises behind you. Looking down into Pico Viejo’s crater, you see the shape of a volcano whose most dramatic phase lies in the past, its summit collapsed and its energy now expressed through the flank vents that still scar the ground below.
A different pace
Teide and Pico Viejo share a foundation, a magma system, and a history. But they represent different paces of volcanic growth. Teide builds, steeply and persistently, its narrow cone rising as the focus of the system’s vertical energy. Pico Viejo spreads and collapses, its broader form shaped by the failure of its own summit and the lateral movement of magma into adjoining fissures.
The most accurate way to see them is as two expressions of the same deep process. The magma chamber beneath the Cañadas caldera feeds both. When the system is active, the conduit can open at the summit of Teide, producing Strombolian bursts and building the cone higher, or at the flank of Pico Viejo, producing long effusive flows that can last months. The 1798 eruption was the most recent example of the latter. The fumaroles at Teide’s summit are the most recent example of the former. The system is not choosing between the peaks. It is using both, at different scales and on different timescales.
Standing on the rim of Pico Viejo you are looking at the crater of the quieter peak. Lower, less famous, easier to reach. But the crater itself tells you that quietness is not the same as inactivity. The 800 m diameter is a record of an event far larger than anything Teide has produced in the Holocene. The banding on its walls is the chemical signature of hydrothermal systems that still operate beneath the complex. And on the flank below your feet, the black lava of 1798 is barely two centuries old. A reminder that the Teide–Pico Viejo complex has not settled into its present shape yet.