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Thursday, May 05, 2022

Garachico, 1706: the worst volcanic eruption in the history of the Canary Islands

Garachico from the sea by the 'new land' formed by the 1706 eruption

Lava from the Trevejo or Arenas Negras volcano, over three centuries ago, swept through one of the most prosperous towns in the archipelago, a disaster that offers many clues about life after a volcanic eruption

At nightfall from May 4 to 5, 1706, earthquakes began to be felt in Tenerife so strong that "sepulchres were seen with the effect of wanting to throw the dead bodies, the bells were heard that with felt blows seemed to ring in agony", according to Friar Domingo Josef Cassares. The tremors preceded an eruption that, without being one of the largest in the archipelago in terms of lava volume or duration, was the one with the largest human and economic footprint in its history. 

"It had a terrible impact, an enormous long-term repercussion, much greater than any other in the history of the Canary Islands," summarizes Carmen Romero, an expert geographer in historical Canarian volcanism. Today, when walking along the seafront avenue of Garachico, we can sit down to have a beer on top of that already firm lava flow and watch tourists take selfies and jump into the water in the natural pools created by the lava.

The Garachico eruption was decisive not only for the town itself, but for the entire archipelago. Its port concentrated a large part of the international trade that linked the island with Europe, Africa and America. But one of the two main lava tongues that swept through the town split the natural cove that sheltered the boats in half, disabling much of that precious port. The activity would move to the port of Santa Cruz, current capital, and many of the inhabitants left the place. "The population did not recover until well into the 20th century," says Romero, from the University of La Laguna (ULL).

The lava flows from the Arenas Negras eruption, so named because the entire area was covered by picón (volcanic gravel), devastated several towns as happened in Todoque (La Palma) on their way to the sea. But on that occasion, the worst was when it reached the coast: it did not lead to banana plantations and cliffs, but to a prosperous city. 

"There was a self-evacuation of the inhabitants of the affected areas, because the authorities did not organize it, as soon as the accretion balls began to fall, causing terrible fires". Those balls are pieces of up to three meters, broken off from the lava, that roll down the ravines and that become infernal projectiles when they reach the buildings.

The lava advanced much faster than from Cumbre Vieja in La Palma, since the flows travelled the 6.5 kilometres to the coast in a single day. The lava on La Palma covered no more than 5 kilometres of distance to the sea in 10 days. In Garachico, seven tongues reached the coast from the Trevejo volcano: the first caused an urgent evacuation on May 5, but the entire town had to leave on the 28th of that month when another threatened to trap those who remained. “The lava flows from La Palma have a morphology and viscosity that those from Garachico did not have,” explains Romero, as the first analyses of that magma spilled on the surface are confirming. That's why they are slower.

The lavas of Arenas Negras covered, after 40 days, an area of ​​more than seven square kilometres; the recent eruption of La Palma covered more than four in three weeks. Both are modest eruptions compared to Timanfaya, which lasted six years from 1730 and changed the entire structure of the island of Lanzarote. But the human impact is different: at the end of the 17th century, Garachico had more than 3,000 inhabitants; after the eruption, less than 500 remained, and there is no documentary evidence of any deaths. The bourgeoisie left the almost useless port. "The network of roads and the water conduction network were cut, which was essential because there were no springs in the lower part of the island," says the geographer. "Just like in La Palma, the lava flows cut off all the communication and supply infrastructures for the population," she adds.

Map of Garachico drawn up by Leonardo Torriani around 1588, a few years before the eruption,
with the sheltered horseshoe-shaped harbor still intact (right).

But there is hope and timely lessons from the case of Garachico and also of Timanfaya. Two Canarian words that are going to be key: entullar, covering the areas covered by the lava with borrowed earth, and sorribar, preparing that new land to cultivate or build on. And a determining concept: the will. “The recovery of the new territories after the lava flows is relatively fast if there is interest and economic capacity”, assures the expert in the historical eruptions of the Canary Islands. Garachico did not recover and lived in the legend of a glorious past: "Later it was said that it had been such a rich city that it had marble pavements," says Romero.

But Garachico did not recover that wealth because there was no intention; the new port was not built until 2012. The powers of the time were more interested in moving the economic flow closer to the capital, then La Laguna, from that remote part of the island, because a lava flow is not a curse that prevents a territory from recovering. Rather the other way around: in the Canary Islands have been creating life and wealth on the lava for centuries, despite the fact that they take the form of malpaís (badlands), that tortuous and arid terrain on which it seems impossible to even walk. 

View of Garachico, Tenerife, Spain Diego Delso, CC BY-SA 3.0

Garachico was the proof: the original town was built on another lava platform, on a fajana (strip) like the one recently created on La Palma. It had risen on a previous delta. It can be seen in the urban fabric, in the form of arches, and when looking at an aerial photo of the city: a fan that unfolds over the sea. In a document from 1541 it is stated: “[Garachico] has been populated and founded very close to the sea, on badlands and cliffs and useless land, and because it is of such quality, and the people who have built their houses, it has been bringing land from another part to entullarlo, breaking big rocks and crags”.

The lava flows that swept it away over 300 years ago are now well-cared for natural pools in which to bathe placidly by the sea. Right next to the magmatic delta that is emerging in La Palma, there is another a little older, created in the San Juan eruption of 1949. La Bombilla is a population centre that was formed shortly after on top of that eruption, because of the lava gave rise to banana plantations. And the Timanfaya eruption, which destroyed villages and lasted more than 2,000 days, meant that Lanzarote now has perfect conditions for growing vines, thanks to the cunning of the locals, who took advantage of the condensation properties of the volcanic rock to pamper them and protect them from the winds.

“You don't remove [the lava]: you put it on top. It is as if it were a pot, you put soil and plants”, summarizes Romero. To build Garachico, it was necessary to entullar: bring soil from another part of the island, borrowed land, put it on the rough surface and generate a flat surface. “It is a common cultivation technique in the Canary Islands, not only in recent volcanoes, in all areas where there are badlands or lava flows. This is an infrastructure that farmers on the islands have been doing for hundreds of years”, highlights the ULL professor. 

Garachico, 1706: cómo se recuperó una villa de la peor erupción volcánica de la historia de Canarias (Via)

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