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. Its highest mountain is the Roque de los Muchachos, 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 , 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, currently 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: The volcano started erupting again on 19th September 2021 after a seismic crisis rocked the island. 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) 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.;. 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. In a programme transmitted by the British Broadcasting Corporation BBC "Horizon" broadcast on 12 October 2000, two geologists (Day and McGuire) cited La Grieta as proof that half of the Cumbre Vieja had moved towards the Atlantic Ocean (Day et al.; 1999, and  Ward and Day, 2001). 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 x10 kg, could slide into the ocean. This could then potentially generate a giant wave, known as a "megatsunami" around high in the region of the islands. The wave would radiate out across the Atlantic and inundate much of the eastern seaboard of North America about 7 hours later, many of the  islands in the Caribbean and northern coasts of South America between six and eight hours later. They estimate that the tsunami will have waves possibly or higher causing massive devastation along the coastlines. Modelling suggests that the tsunami could inundate up to inland – depending upon topography. The basis for Ward and Day (2001) modelling the collapse of a much larger portion of the western flank than what the currently visible surface crack indicates as being potentially unstable, was based on geological mapping by Day et al.; (1999). In this paper they argue that a large part of the western flank  has been constructed in the scar of a previous collapse and therefore sits upon unstable debris. However, nowhere in their paper do Ward and Day, (2001), make any claim about the imminent collapse of the flank. They state that they have modelled the worst-case scenario, and as a result they state "a future collapse has the potential to cause a tsunami which may devastate the east coast of the USA and other locations". The claim was also explored in a BBC docu-drama called "End Day" which went through several hypothetical scenarios of disastrous proportions. In 2002 the Tsunami  Society (Pararas-Carayannis, 2002), published a statement stating "... We would like to halt the scaremongering from these unfounded reports..." The major points raised in this report include: A survey carried out by Moss et al.; (1999) reported that the western flank is stable with no indication of aseismic creep being recorded. In 2001 Carracedo et al.; stated that they consider the 1949 crack to be a shallow and inactive surface expression. They do suggest that the crack should be monitored, but consider the possibility that the edifice is unstable as being almost non-existent. Murty et al.; (2005) claim that  the morphology of the Atlantic Ocean prevents the generation and propagation of trans-oceanic tsunamis. However the Tohoku tsunami of 2011 propagated to Hawaii and the coast of California, a distance much greater than a trans-Atlantic crossing. In 2006 professor Jan Nieuwenhuis of Delft University of Technology simulated several volcanic eruptions and calculated it would take another 10,000 years for the flanks to become sufficiently high and unstable to cause a massive collapse., A 2008 paper looked into this very worst-case scenario, the most massive slide that could happen (though unlikely and probably impossible right now with the  present day geology). They find wave heights in the range 10 to 188 meters in the Canary Isles themselves. But the waves interfere and dissipate as they head out into the Atlantic. They predict 40 meters height for some nearby island systems. For continents, the worst effects are in Northern Brazil (13.6 m), French Guiana (12.7 m), mid-US (9.6 m), Western Sahara (largest prediction at 37 meters) and Mauritania (9.7 m). This is not large enough to count as a megatsunami, with the highest prediction for Western Sahara comparable to the Japanese tsunami, so it would only be a  megatsunami locally in the mid Atlantic. An underwater eruption that began in September 2011 south of the island of El Hierro gave rise to more speculation about the possibility of a megatsunami. As each island in the archipelago is an independent edifice often several tens of kilometres away from the adjacent island it is geologically impossible that volcanic activity on one island will influence the other islands. El Hierro lies about 100 km south of La Palma, over 100 km south-west of Tenerife. La Gomera – extinct since about 4 million year BP, Gran Canaria and Fuerteventura no eruptive history  since about 10000 years BY, Lanzarote last erupted in the 19th century. On Saturday and Sunday 7–8 October 2017, a series of minor tremors sparked panic on the Canary Islands, bringing up the topic again and asking how long the island will last until the next eruption/quake and how they will prepare for such an event. The north of the Spanish archipelago was struck by a 3.5 magnitude quake on 24 October 2017 at 8.25pm. Climate. La Palma has a mild and consistent warm subtropical hot semi-arid climate which in the Köppen climate classification is represented as "BSh . The winters are warm and the summers are very warm. It has significant influences of the maritime mediterranean climate due to its quite wet winters. For a Canary island, the weather is quite cloudy, as La Palma is far more exposed to marine air systems than easterly islands, caused by the Canary Current. The inland parts of the island have a more humid climate (Köppen: Csa") which leads to very humid, laurisilva cloud forests in the center of the island, such as the Bosque de los Tiles Natural Park. Naming. In Spanish the island is called "Isla de la Palma ," and is usually abbreviated to "La Palma," which means the Island of Palms or Palm Island. La Palma is nicknamed "Isla Bonita" ("beautiful island") or "Isla Verde" ("green island"). Government. The island is part of the province of Santa Cruz de Tenerife. The island is divided into 14 municipalities: La Palma has a "sister city" relationship with El Dorado Hills, California. Economy. The local economy is primarily based on agriculture and tourism. "Plátanos" (or bananas) are grown throughout the island with many banana farms on the western side of the island in the valley of "Los Llanos de Aridane". Other  crops include: "Strelitzia" (bird of paradise) flowers, oranges, avocados and grapes (which grow well in the volcanic soil). The wine from the grapes is prized. Local ranchers raise endemic cows, sheep and goats (from which they make goat cheese). Fishermen operating from Santa Cruz de La Palma, Tazacorte, and Puerto Naos catch fish for the local markets. Flora and fauna. La Palma has abundant plant life, including several endemic species. Although large areas have been deforested, the upland areas of La Palma retain some of the evergreen temperate cloud forest, or "laurisilva" (laurel forest), where species of Lauraceae, such as  Laurus azorica, "Persea indica", and "Ocotea foetens" are a characteristic component. This is a relic of the Pliocene subtropical forests which used to cover the island. The Canary Island pine ("Pinus canariensis") is found on all of the western Canary Islands, but it is particularly abundant on La Palma. The pine forests are home to two recently discovered and extremely rare La Palma endemics: "Lotus eremiticus" and "L. pyranthus". "Spartocytisus supranubius", a white-flowered broom known locally as Retama del Teide, is native to La Palma and Tenerife, being restricted to the alpine/subalpine habitats present only in these two  islands. Like Tenerife, La Palma also has its own alpine violet, "Viola palmensis". "Echium pininana" (Tree echium) is endemic to La Palma and the tallest species in the genus, reaching over 4 m. It is related to "Echium wildpretii" ("Tower of jewels") which occurs, with separate subspecies, in the subalpine zone of both Tenerife and La Palma. Both species are monocarpic, producing a massive terminal inflorescence. "Echium webbii", a branched shrub with several smaller, dark blue flower spikes, is another island endemic with close relatives on Tenerife. The daisy family (Asteraceae) comprises several La Palma endemics such as "Sonchus palmensis , Argyranthemum haouarytheum" "Pericallis papyracea" and "Cheirolophus sventenii". Several animals are native or endemic to La Palma, including the: In addition, many other animals have been introduced, including rabbits and Barbary sheep, or aoudads, which have become a serious threat to endemic flora A biosphere reserve was established in 1983, and extended and renamed in 1997 and 2002 Natural symbols. The official natural symbols associated with La Palma are the Red-billed chough (Graja) and "Pinus canariensis" (Canary Island pine). History. At the time of European colonization, the Canary Islands were inhabited by native Canarians, referred to collectively as Guanches, although  the natives of La Palma are more correctly known as "Auaritas" (See Canary Islands in pre-colonial times). The origin of these natives is unclear but they are believed to share common ancestry with the Berbers of North Africa. The Guanches had a Neolithic culture divided into several clans led by chiefs. Their name for La Palma was Benahoare. The main remnants of this culture are their cave dwellings, enigmatic petroglyphs and paved stone paths through the mountains. After the Spanish occupation of La Palma, the native Canarians vanished by either being killed, sold into slavery or by assimilating into  the Spanish population. It is believed that the Canary Islands were known to the Phoenicians and Greeks, but the earliest written evidence is by the Roman writer Pliny The Elder, who quoted Juba II of Numidia, but Juba's writings were subsequently lost. The Genoese navigator Lancelotto Malocello reached the archipelago in 1312 and remained for two decades until expelled by a native uprising. In 1404 the Spaniards began the conquest of the islands. Though the first landing on La Palma was in 1405, it took until 1493 and several bloody battles until the last resistance of the natives was  broken. The conqueror of La Palma was Alonso Fernández de Lugo, who defeated Tanausu, the last king on the island. He ruled the area known as Acero (Caldera de Taburiente). Tanausu was ambushed after agreeing to a truce arranged by Fernández de Lugo and Juan de Palma, a Guanche who had converted to Christianity and who was a relative of Tanausu. For the next two centuries, settlements on La Palma became rich as the island served as a trading post on the way to the New World. La Palma received immigrants from Castile, Majorca, Andalusia, Portugal and Catalonia. Religion. The  island is predominately Roman Catholic and since 1676, has been known for the festival of Fiestas Lustrales de la Bajada de la Virgen de las Nieves (the bringing down of the Virgin of the Snow, "Virgen de las Nieves"), which has a rich history, from the time of the Bishop of the Canaries, Bartolomé García Ximénez. The festival features the dancing of "enanos" or midgets. The costumes that people wear have a hole at the top of the hat to allow them to see out, while giving the appearance of dancing midgets. People come from all over the world for  the celebration which happens every five years. The image of the Virgin is taken down from her sanctuary (located in a hilly area on the outskirts of Santa Cruz de La Palma) and paraded around the city of Santa Cruz with the festival lasting nearly two weeks before she is returned. The last time this event was performed in 2015 and the next will be in 2025, as in 2020 had to be cancelled due to the global pandemic of COVID-19. The Virgin of the Snow is the patron saint of La Palma. Many women on the island have the  name "Nieves" in her honor. Every 5 August the annual festival of the Virgin is celebrated. Transport. La Palma has a road network of some . All the main roads are asphalted and in a good state, although there are many sharp bends, some very narrow. In order to reach some small hamlets in the north of the island it is necessary to travel on earth tracks. A good paved road approximately , circumscribes the island. Several bus routes exist that unite the main localities on the island. There is a road that runs from Los Llanos de Aridane to the capital  city of the island Santa Cruz de La Palma (known by locals as simply "Santa Cruz"). This road is a two-lane highway that includes a pair of two-lane tunnels that go right through the top of the mountain. The older tunnel is shorter () and higher than the newer tunnel (). When traveling from one side of the mountain to the other it is common to enter one side in complete clouds (the east side) and come out to the sunny side (western side). This is due to the clouds not being able to cross the mountains, an effect caused  by the counter trade wind. The International La Palma Airport serves the island, and several airlines run services to and from it. There is also ferry service to and from the island in the city of Santa Cruz de La Palma. Water tunnels. The most famous structures of La Palma are the "minas galerias" (water tunnels) which carry the water from sources in the mountains to cities, villages and farms (nowadays mainly banana plantations). La Palma receives almost all of its water supply due to the "mar de nubes" (sea of clouds), stratocumulus cloud at 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 above sea level, a number of international astronomical observatories have been built on the Roque de los Muchachos. The particular geographical position and climate cause clouds to form between and , 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: In addition, the Cherenkov Telescope Array is planned for  construction starting in 2021. In 2021 the Visitors Center of Roque de Los Muchachos will be inaugurated.