La Palma

La Palma (, ), also known as ''La isla bonita'' () and officially San Miguel de La Palma, is the most north-westerly island of the Canary Islands, Spain. La Palma has an area of making it the fifth largest of the eight main Canary Islands. The total population at the end of 2020 was 85,840, of which 15,716 lived in the capital, Santa Cruz de La Palma and about 20,467 in Los Llanos de Aridane, at , being second among the peaks of the Canaries only to the peaks of the Teide massif on Tenerife.

In 1815, the German geologist Leopold von Buch visited the Canary Islands. It was as a result of his visit to Tenerife, where he visited the Las Cañadas caldera, and then later to La Palma, where he visited the Taburiente caldera, that the Spanish word for cauldron or large cooking pot – "caldera" – was introduced into the geological vocabulary. In the center of the island is the Caldera de Taburiente National Park; one of four national parks in the Canary Islands.

Origins and geology

La Palma, like the other islands of the Canary Island archipelago, is a volcanic ocean island. The volcano rises almost above the floor of the Atlantic Ocean. There is road access from sea level to the summit at ,ISTAC
"Instituto Canario de Estadistica" (In Spanish). Retrieved 24 April 2009 which is marked by an outcrop of rocks called Los Muchachos ("The Lads"). This is the site of the Roque de los Muchachos Observatory, one of the world's premier astronomical observatories.

La Palma's geography is a result of the volcanic formation of the island. The highest peaks reach over above sea level, and the base of the island is located almost below sea level. The northern part of La Palma is dominated by the Caldera de Taburiente, with a width of and a depth of . It is surrounded by a ring of mountains ranging from to in height. On its northern side is the exposed remains of the original seamount. Only the deep Barranco de las Angustias ("Ravine of Anxiety") ravine leads into the inner area of the caldera, which is a national park. It can be reached only by hiking. The outer slopes are cut by numerous gorges which run from down to the sea. Today, only a few of these carry water due to the many water tunnels that have been cut into the island's structure.

From the Caldera de Taburiente to the south runs the ridge Cumbre Nueva ('New Ridge', which despite its name is older than the Cumbre Vieja, 'Old Ridge.') The southern part of La Palma consists of the Cumbre Vieja, a volcanic ridge formed by numerous volcanic cones built of lava and scoria. The Cumbre Vieja is active, last erupting in the 2021 La Palma eruption, which destroyed more than 2600 buildings and caused one death. Beyond Punta de Fuencaliente at the southern tip of the island, the Cumbre Vieja continues in a southerly direction as a submarine volcano.

Volcanism and eruptions

Like all of the Canary Islands, La Palma originally formed as a seamount through submarine volcanic activity. La Palma is currently, along with Tenerife, the most volcanically active of the Canary Islands and was formed three to four million years ago. Its base lies almost below sea level and reaches a height of above sea level. About a half a million years ago, the Taburiente volcano collapsed with a giant landslide, forming the Caldera de Taburiente. Erosion has since exposed part of the seamount in the northern sector of the Caldera. Since the Spanish have kept records, there have been eight eruptions – all of which have occurred on the Cumbre Vieja:

* 1470–1492 Montaña Quemada
* 1585 Tajuya near El Paso
* 1646 Volcán Martín
* 1677 Volcán San Antonio
* 1712 El Charco
* 1949 Volcán San Juan: Duraznero, Hoyo Negro and Llano del Banco vents
* 1971 Volcán Teneguía
* 2021 Cumbre Vieja volcanic eruption

At Cumbre Vieja ridge a new monogenetic volcano burst on 19 September 2021 after several seismic crisis that rocked the island, among other anomalies regarding volcanic surveillance.

Tsunami scenarios

During the 1949 eruption – which commenced on the festivity of San Juan (St John) 24 June 1949 at the Duraznero, and 8 July 1949 Llano del Banco vents on the Cumbre Vieja – an earthquake, with an epicentre near Jedey, occurred. This is considered to have caused a crack which Bonelli Rubio (1950)Bonelli Rubio, J. M., 1950. Contribucion al estudio de la erupcion del Nambroque o San Juan. Madrid: Inst. Geografico y Catastral, 25 pp. named "La Grieta" – (the crack), to form, with a width of about and a depth of about . It attains a maximum displacement of ~ in the vicinity of the Hoyo Negro to Duraznero vents. It is not traceable southward from the Duraznero vent. North of the Hoyo Negro it traverses downslope and is traceable for ~1500 m. The total distance from the southern rim of the Duraznero vent to the Llano del Banco is ~4 km. In 1951 Ortiz and Bonelli-Rubio published further information in respect of the eruption and associated phenomena that occurred before and during the eruption. There is no indication that the crack has penetrated the edifice of the volcano, and, due to the absence of Minas Galerias (water tunnels) within the Cumbre Vieja, there is no possibility of examining the internal structure of the flank. Carracedo et al.Carracedo, J. C; Badiola, E. R; Guillou, H; de la Nuez, J; and Pérez Torrado, F. J; 2001. Geology and Volcanology of La Palma and El Hierro, Western Canaries. Estudios Geol. 57, (5–6) 175–273. This means that despite popular claims that the flank is in danger of failing, the status of the flank and any actual risk, are not yet scientifically verified.

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