1. Origins and geology

2. Volcano
    Tsunami scenarios 

3. Observatories

4. See also

5. References

6. External links

La Palma ({{IPA-es|la ˈpalma}}), also San Miguel de La Palma, is the most north-westerly island of the Canary Islands, Spain. La Palma has an area of 706 km² making it the fifth largest of the seven main Canary Islands. The total population is about 81,863^[2], of which 18,000 (2003 data) live in the capital, Santa Cruz de la Palma and about 20,000 (2004 data) in Los Llanos de Aridane. La Palma has "sister city" status with El Dorado Hills, California. Its highest mountain is the Roque de los Muchachos, at 2,426 metres, 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 {{convert|7|km|0|abbr=on}} above the floor of the Atlantic Ocean. There is road access from sea level to the summit at {{convert|2426|m|0|abbr=on}},^[3] 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 {{convert|2400|m|0|abbr=on}} above sea level, and the base of the island is located almost {{convert|4000|m|0|abbr=on}} below sea level. The northern part of La Palma is dominated by the Caldera de Taburiente, with a width of {{convert|9|km|0|abbr=on}} and a depth of {{convert|1500|m|0|abbr=on}}. It is surrounded by a ring of mountains ranging from {{convert|1600|m|0|abbr=on}} to {{convert|2400|m|0|abbr=on}} 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 {{convert|2000|m|0|abbr=on}} 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 – the 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 – but dormant, with the last eruption occurring in 1971 at the Teneguía vent which is located at the southern end of the Cumbre Vieja – Punta de Fuencaliente, (The Point of the Hot Fountain). Beyond Punta de Fuencaliente, the Cumbre Vieja continues in a southerly direction as a submarine volcano.

Volcano

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 {{convert|4000|m|0|abbr=on}} below sea level and reaches a height of {{convert|2426|m|0|abbr=on}} 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 occupation, there have been seven eruptions – all of which have occurred on the Cumbre Vieja:

• 1470–1492 Montaña Quemada
• 1585 Tajuya near El Paso
• 1646 Volcán San Martin
• 1677 Volcán San Antonio
• 1712 El Charco
• 1949 Volcán Nambroque at the Duraznero, Hoyo Negro and Llano del Banco vents
• 1971 Volcán Teneguía

During the 1949 eruption – which commenced on the fiesta 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 Jedy, occurred. This is considered to have caused a {{convert|2.5|km|1|adj=mid|-long}} crack which Bonelli Rubio (1950)^[4] named "La Grieta" – (the crack), to form, with a width of about {{convert|1|m|0|abbr=on}} and a depth of about {{convert|2|m|0|abbr=on}}. It attains a maximum displacement of ~{{convert|4|m|0|abbr=on}} 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. It should be noted that 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.^[5] 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.;^[6]. This means that claims that the flank is in danger of failing are unfounded.{{original research inline|date=February 2018}} However the lack of supporting evidence has not stopped claims that the flank is in danger of failing.

Tsunami scenarios

In a programme transmitted by the British Broadcasting Corporation BBC Horizon broadcast on 12 October 2000, two geologists (Day and McGuire) cited this crack as proof that half of the Cumbre Vieja had moved towards the Atlantic Ocean (Day et al.; 1999,^[7] and Ward and Day, 2001^[8]). They postulate that this process was driven by the pressure caused by the rising magma heating water trapped within the structure of the island. They hypothesised that during a future eruption, the western flank of the Cumbre Vieja, with a mass of approximately 1.5 x10¹⁵ kg, could slide into the ocean. This could then potentially generate a giant wave which they termed a "megatsunami" around {{convert|650|m|0|abbr=on}}//Caribbean">Caribbean and northern coasts of South America between six and eight hours later. They estimate that the tsunami will have waves possibly {{convert|50|m|0|abbr=on}} or higher causing massive devastation along the coastlines. Modelling suggests that the tsunami could inundate up to {{convert|25|km|0|abbr=on}} inland – depending upon topography. The basis for Ward and Day (2001)^{[{{convert|1600|m|0|abbr=on}} altitude, carried on the prevailing wind which blows from the north-east trade winds. The water condenses on the long needles of the trees and other vegetation, it then either drips onto the ground or runs down the trunk etc., into the ground. Eventually it collects inside the rock-strata, and is then drained via the galerias into aqueducts and pipes for distribution. The galerias have been cut into the rocks over centuries. To visit the galerias a permit is required. It is possible to walk alongside many of the aqueducts, a popular activity for tourists (similar to the levadas of Madeira). The tour to the Marcos y Corderos waterfall and springs is also popular.}

There is an extensive network of irrigation canals in the valley of Los Llanos de Aridane. These canals carry water from the mountains throughout the valley and allow for the cultivation of bananas, avocados, flowers, and other plants. Each farmer gets a scheduled "turn" to fill an irrigation tank with water 24 hours of the day. If a farmer's turn is at 2 AM he will wake up and make sure to fill his tank when possible so as to have sufficient water for his farm.

These round tanks typically gather moss and lilly pads upon which frogs make their habitat.

Observatories

Due to the location of the island and the height of its mountains, some {{convert|2400|m|0|abbr=on}} above sea level, a number of international observatories have been built on the Roque de los Muchachos. The particular geographical position and climate cause clouds to form between {{convert|1000|m|0|abbr=on}} and {{convert|2000|m|0|abbr=on}}, usually leaving the observatories with a clear sky. Often, the view from the top of the volcano is a sea of clouds covering the eastern part of the island. Telescopes at the observatory include:

• The Isaac Newton Group of Telescopes (ING) operates three telescopes: the {{convert|4.2|m|0|abbr=on}} William Herschel Telescope, the {{convert|2.5|m|0|abbr=on}} Isaac Newton Telescope and the {{convert|1|m|0|abbr=on}} Jacobus Kapteyn Telescope.
• The {{convert|2.5|m|0|abbr=on}} Nordic Optical Telescope (NOT).
• The {{convert|1|m|0|abbr=on}} Swedish 1-m Solar Telescope (SST) operated by the Institute for Solar Physics.
• The {{convert|0.45|m|0|abbr=on}} Dutch Open Telescope (DOT).
• A {{convert|0.6|m|0|abbr=on}} optical telescope.
• The Carlsberg Meridian Telescope (CMT).
• The {{convert|1.2|m|0|abbr=on}} Mercator Telescope.
• The {{convert|2|m|0|abbr=on}} Liverpool Telescope.
• The {{convert|10.4|m|0|abbr=on}} Gran Telescopio Canarias (Great Canary Telescope, dedicated 24 July 2009).
• The {{convert|3.6|m|0|abbr=on}} Telescopio Nazionale Galileo (TNG).
• The {{convert|17|m|0|abbr=on}} MAGIC Telescope, an air shower Cherenkov telescope for observing high energy gamma rays
• The SuperWASP-North telescope, used to detect extrasolar planets.

The DOT and the SST have been specifically built to study the Sun.

See also

• List of volcanoes in Spain

References

External links

• Official Tourism Website
• Official La Palma Website (Spanish)
• La Palma – The official website of the Canary Islands
• Stargazing Sites on La Palma

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