Tajogaite
Updated: May 19
La Palma's Cumbre Vieja volcano eruption of 2021
Characteristics
The eruption of Tajogaite occurred in the end of 2021. It is a fissure-fed monogenetic—a volcanic vent which is active only once—cinder (scoria) cone, characterized by Strombolian activity with lava-fountaining episodes (paroxysms) as well as phreatomagmatic pulses, with one large final explosion of Vulcanian type. It is located on the Canary Island of La Palma, Spain, at the northwestern end of the subaerial section of the Cumbre Vieja volcanic ridge, of which it is just one of many vents. The eruption took place in a forested area called Hoya de Tajogaite, which is located in Cabezavaca (a.k.a. Cabeza de Vaca "cow head"), and belongs to the section of Las Manchas of El Paso municipality.
The eruption of Tajogaite has surpassed all previous subhistorical and historical eruptions on La Palma in terms of quantity of expelled materials, duration, and intensity: It expelled 215×10⁶ m³ of volcanic material (almost as much as all the previous other 6 historical eruptions of La Palma combined); covered an area of 1,237.3 ha with lava fields, lasted for a total of 85 days and 8 hours; attained a volcanic explosivity index (VEI) of 3; and produced 9,090 earthquakes.
Subhistorical eruptions on La Palma are represented by a single event:
Tacande, Tacante or Montaña Quemada: VEI 2, 1470-92, 462 ha (unknown duration).
Historical eruptions on La Palma occurred as follows:
Tehuya, Tahuya, Tihuya, Roques de Jedey or Los Campanarios: VEI 2, 1585, 24×10⁶ m³, 400 ha, 84 days.
San Martín, Tigalate or Tagalate: VEI 2, 1646, 26×10⁶ m³, 610 ha, 82 days.
San Antonio: VEI 2, 1677-78, 66×10⁶ m³, 446 ha, 66 days.
El Charco or Montaña Lajiones: VEI 2, 1712, 41×10⁶ m³, 535 ha, 56 days.
San Juan (western vent of Llano del Banco and eastern craters of Nambroque, Hoyo Negro and Duraznero—the latter two jointly known as Las Deseadas): VEI 2, 1949, 51×10⁶ m³, 392 ha, 47 days.
Teneguía: VEI 2, 1971, 31×10⁶ m³, 317 ha, 24 days.
Tajogaite: VEI 3, 2021, 215×10⁶ m³, 1,237.3 ha, 85 days and 8 hours (Sept. 19 14:11 UTC—Dec. 13 22:21 UTC).
The eruption has shown both great explosive and effusive activity, emitting a total of 215 million m³ of volcanic material (lava flows and tephra), almost as much as all the previous other 6 historical eruptions of La Palma combined. Initially, tephrite was emitted; and since late September, basanite.
At least 6 eruptive fissures spanning 557 m in a north-easterly direction produced the new scoria cone about 700 m long at the base and 200 m tall—as opposed to Teneguía's which is 77 m tall—at 1,121 m above sea level with a volume of 34 million m³. The violent pulsating lava fountains have reached heights of up to 600 m, expelling a total of over 20 million m³ of tephra. Volcanic bombs—tephra larger than 64 mm and up to several meters—were thrown up to 1.5 km from the eruptive vents.
Over 160 million m³ of lava flows have been emitted, more than in the eruptions of San Juan (1949) and Teneguía (1971) combined, making it the third most significant eruption in the history of the Canary Islands, only behind Timanfaya in Lanzarote (1730-1736; 1 billion m³) and the submarine eruption of Tagoro in El Hierro (2011; 329 million m³). Lava flow morphology was mostly ʻaʻā, with some pāhoehoe. The eruption has buried under lava an area larger than any previous registered eruption. The lava flows have spread to 1,237.3 hectares, although only the emerged part of the streams is considered and the total surface is slightly higher. The subaereal lava flows measure 3,350 m wide by 6.5 km long, with an additional 1.1 km-long submarine portion, and normally reach between 10 and 20 m in height, and 70 m in watercourses. Their highest recorded temperature was 1,140 °C. Several lava flows have reached the Atlantic Ocean. The subaereal portion of the lava deltas—known locally as "fajanas", a term used for both lavatic and detrital deposits—that were formed in the sea at Los Guirros Beach in Tazacorte have added 48.02 ha to Spain's territory, 4 hectares larger than Vatican City. The area of the submarine lava deltas, on the other hand, is larger than 21 ha.
The average duration of the eruptions on La Palma is 60 days, and up until recently there has been a constant decreasing tendency since the 84 days that the Tehuya eruption (1585) lasted to the 24 days of Teneguía (1971). However, Tajogaite has broken this dynamic and has surpassed Tehuya as the most long-lived registered eruption in 431 years.
For its first two months, the eruption was assigned a rating on the Volcanic Explosivity Index (VEI) of VEI 2 (on a scale of 8). On 20 November 2021, the scientific committee of the Canary Islands Volcanic Emergency Plan (Pevolca) raised the rating from VEI 2 to VEI 3. Though in modern eruptions where it can be measured, eruption column height is often seen as a more accurate measure, in this case the change was based on the 10 million m³ of ejected tephra measure alone. The ash plume was typically 3.5 km high, but has reached heights of 7 km on several occasions causing effects that were felt in Morocco, Western Europe and the Caribbean, and reaching a maximum height of 8.5 km on December 13 during the Vulcanian explosion. As for gas emissions, Tajogaite has emitted 56,000 tons of SO₂ on its first day and 400,000 tons in only a little over 3 weeks, more than all active volcanoes throughout all of 2020, breaking the world record and surpassing the previous holder of the title, Miyakejima volcano in Japan. The total amount, however, is approximately 2 million tons (2 teragrams).
The strongest earthquake since the start of the eruption in September, as well as the entire seismic crisis which started in 2017, occurred on November 19 at 01:08:47 UTC, and registered at 5.1 mBLg at 36 km depth underneath the centre of Cumbre Vieja. The highest felt seismic intensity—ranking based on the observed effects of an earthquake in each particular place—was IV-V (EMS). The average depth at which the earthquakes occurred was at 15 km, and were mostly located between 40 and 35 km and 15 and 10 km depth, with the deepest one at 45 km (Nov 22, 2021 19:20 GMT), and the shallowest one registered at barely 1 km. On November 30, seismic activity reached a record number of 374 quakes of magnitudes above 2 during a 24 hour window. The total amount of registered earthquakes was 9,090. The most acute vetical deformation was registered at 33 cm on October 24, in LP03—the nearest station to the volcanic cone. The accumulated released seismic energy has been 6.3×10¹³ joules ≈ 175 million MWh.
The eruption has caused widespread damage on the island. Only in the first 3 days the damage has exceeded the value of €906.8 million. The vast lava flows have completely destroyed the three towns of El Paraíso, Todoque and La Laguna, and partially that of Las Manchas. It has forced about 7,000 people to flee and leaving 1,307 people homeless. 2,988 buildings, nearly 60 km of roads, 260 hectares of crops (145.61 ha of banana plantations, 53.54 ha of vineyards and 22.89 ha of avocado plantations) have been buried beneath the lava. It ranks among the most devastating volcanic eruptions in the recent history worldwide.
Summary of the eruption
Background
Since October 2017 until June 2021, up to 8 earthquake swarms were registered under the Cumbre Vieja volcanic ridge. On September 11, 2021, a new earthquake swarm of low intensity occurred in the south of the island. It slowly migrated to the surface, with earthquakes up to around 3.5 on the Richter scale, and over 25,000 recorded in the space of 10 days. On September 13, 1,500 small earthquakes were registered in Cumbre Vieja.
September
Main article: Tajogaite (September)
After a magnitude 4.2 earthquake on September 19 at 14:11 UTC, the volcano started erupting, and lava started flowing through a crack located between El Frontón and Hoya de Tajogaite, in a valley-like landscape near Montaña Rajada. The eruption started with the opening of little fissures of the ground following directions prefixed by the main structural patterns of the island. From the first moments, this fissuration was accompanied by the emission of gases and small lava fountains from several points along the whole extension of the main fissure that attained several kilometres in length. Within a short time during the first hours of the event, these multiple incipient volcanic vents remained restricted to a few ones, increasingly active, where the construction of heaps of tephra gradually grew and coalesced to the typical volcanic cone with its corresponding craters. By September 21, the eruption had caused damage likely to exceed the value of €400 million. Throughout the last week of September, the eruption experienced a more explosive phase due to a slower ascent of the magma that allowed gases to concentrate and explode, releasing a 4,500 m tall ash plume and volcanic bombs of one meter thrown up 400 m in the air. Record highs of more than 50,000 tons of sulphur dioxide a day were recorded. The aerosol plumes from the eruption continued to travel along northern Africa and south Europe reaching Morocco, Tunisia, Algeria, Libya, a large part of Iberian Peninsula and the Mediterranean coasts of France and Italy. On September 29, the lava flow reached the ocean for the first time, passing north of the cinder cone of Montaña Todoque, to arrive and descend at the sea cliff at Playa Nueva, generating acid clouds of hot steam. By the end of the month, the eruption had expelled almost 80 million m³ of lava, covering over 230 hectares of the island, completely destroying 630 buildings and infrastructures and around 20 km of roads. In only 11 days, the eruption expelled nearly twice as much lava as the Teneguía did in 24 days. Initially, tephrite was expelled; and since late September, basanite. These variations of the chemistry and mineralogy of the lavas were related to the different stages of the eruption.
October
Main article: Tajogaite (October)
On October 4, voluminous lava flows invade the cone's flanks as the crater area partially collapses. Approximately one week into the month of October, the eruption was characterized by highly noisy, energetic, sustained and near-constant explosions, causing strong vibration of soil, vehicles and windows in a range of more than 5-6 km around the vents. Volcanic lightning over the eruption was first seen on October 11, triggered by the friction of colliding pyrocslasts within the thick plume. On October 13, the eruption expelled over 400,000 tons of SO₂, more than all active volcanoes throughout all of 2020, breaking the world record and surpassing the previous holder of the title, Miyakejima volcano. The explosive activity decreased a lot on October 16 and was often absent, and the eruption became dominantly effusive. This would however change on October 19 when the eruption intensified once again, with the upper vents producing vigorous explosions and pulsating lava and ash fountains, and the lower vents feeding the lava flow. By October 22, there were 7 active vents from which different materials emanated. Each of the 4 vents of the main cone presented its own characteristic activity, which was as following from west to east (upslope): a first Hawaiian vent which solely emitted pāhoehoe lava flows; a second pulsating Hawaiian vent with gases; a third vent which emitted gases and water vapor; and a fourth Strombolian vent which emitted pyroclasts and gases. Due to the considerable slope of the terrain in the direction in which the fissure opened, high pressure lava fountains, pyroclastic materials and gases were emitted mostly from the higher volcanic vents, while from the lower vents only more or less degasified lava poured out with a much lower explosivity. This is because in upper vents, gas bubbles usually form a type of conduit within the magma column, causing magma to erupt as gas jets with little liquid and more ash; whereas areas at the margins of the main column might be largely degassed on the other hand, and these will form liquid, but lower fountains or entirely effusive vents. The secondary cone, 300 m away from the main one, possesses a phreatomagmatic vent which emits water vapor, gases and ashes. External water—from the groundwater system—sometimes interacts with the magma. Depending on how much water is present and able to interact with the magma, this interaction can completely change the dynamics of the activity at some or even all vents. Water can absorb a lot of energy, but if in contact with magma, it typically transforms into steam as result, which goes with a thousand times increase of volume. If the generated steam is not easily released, it becomes over-pressured, and once this pressure overcomes the surrounding containing pressure, it will result in violent explosions known as phreatomagmatic. Phreatomagmatic activity is more likely to occur at the vents furthest away from the center, where magma rises through older rock layers that might still contain water or are in connection with aquifers. On October 25, the pulsating Hawaiian vent collapsed, giving way to short-lived floods of lava gushing out of the destroyed lava lake. This was followed on the next day by a slight decrease in effusive and explosive activity. However, vertical ground deformation of 10 cm heralded a great increase in explosiveness, with 600 m-tall lava fountaining at the main vent and other vents producing dense ash. In accordance with an increase in the number of earthquakes in the last week of October, the explosive activity remained very high into the month of November, with a 5.1 magnitude earthquake on October 30. In October, the main cone reached its current height of 200 meters from its base.
November
Main article: Tajogaite (November)
Volcanic tremor decreased in the first week of November, whereas gas emissions and ground deformation increased, and elemental sulphur is seen for the first time on the cone, indicating a clear change in the dynamic of the eruption. On November 6, activity picks up punctually and the ground inflates 10 cm in 24 hours, but the activity continues to steadily slow down afterwards. On November 9, the lava flows reach coast again, and enter the ocean at Playa de Los Guirres. While the activity remains stable, lava keeps flowing into the ocean during the coming days. On November 16, the eruption intensifies again, at first with occasional small lava fountaining and moderate ash emissions at the summit vents, but it would become increasingly violent in the course of the coming days, with intense internal and external activity in the form of increased seismicity, volcanic tremor, strong ash emissions and more surface lava flows near the vent as well as downslope. But the eruption shifted most of the visible activity to the vents again on November 19, where lava surged out in a short flood, possibly due to a collapse in the northern wall of the cone, and a new voluminous lava flow travelled downhill from the cone which could be due to a temporary increase in magma supply or a decrease of the amount of lava going into the tube system as a result of a blockage. The activity decreases somewhat, but lava continues to cover new land. On November 22, lava flow #7 reaches the ocean, creating a third lava delta. A second branch of the active lava flow, travelling south of the main one, yet again reached the ocean, causing massive rockfalls at the sea cliff. Despite the spectacular lava flows, the eruption coninues on a decreasing trend. The weaker activity changed dramatically on the morning of November 25 AT 09:00 UTC, when an episode of sudden increase in the emission of lava occurred at the main effusive vent, and around 11:00 UTC a new voluminous and very liquid lava flow began to pour out towards the southwest, travelling parallel to the previous flow labelled #10. Later that same day, at 17:15 UTC, a new fissure opened less than 1,000 m south of the main cone, with one of the effusive vents appeearing right next to a house, feeding a new lava flow for the next two days that quickly reached Las Manchas at 600 m/h. Another surge of lava occurred at the main cone, generating a spectacular dome-shaped lava fountain at the lower vent while ash- and gas-rich fountains were jetting from the main vent. The activity started to get calmer on November 27, but increasing inflation indicated that more lava was being stored at depth than currently erupted, announcing a new surge of magma. During the course of the eruption, secondary cracks and fissures developed upslope near the main volcanic vents following also the main structural trends of the island, likely because the older conduits at the cone have become too high and too inaccessible compared to creating new fissures at the base of the cone. On the morning of November 28, several new vents opened at the northern and northeastern base of the main cone, producing lava fountains and emitting new lava flows that travel around the northern side of the cone. The lava flows from the new vents quickly crossed the Tacande road and enlarged the northern margin of the flow field, covering new so-far untouched land in that part. By now, the eruption already counted as the largest on La Palma Island in over 500 years, likely overtaking the 1585 eruption at Tahuya as the largest by volume eruption on the island in recorded history. The latter erupted approximately 300 million m³ of lava, while the volume of this eruption was already estimated to be at about this value at this point. As to the other lava flows, activity continued to feed them as well. On the last day of November, the lava flow activity decreased, while seismic activity reached a record number of almost 374 quakes of magnitudes above 2 during 24 hours. The total area covered by lava flows, including the lava deltas, stood at 1,151 hectares. The activity remained intense into the month of December.
December
Main article: Tajogaite (December)
On the night of December 1, Strombolian activity increased at the new vent system on the northeastern side of the cone, with tall and sustained lava fountaining at the main vent. On the next morning, the activity dropped again significantly, but a new signal of ground uplift announced a new batch of magma that was on the rise and being stored. On December 4, the calm came to an and and the new magma arrived at the vents causing short-ived overflow of lava. From the next day onwards, activity started decreasing, with only intermittent and weak pulses of Strombolian activity and occasional ash emissions of 2-3.7 km in altitude could be seen at the vents. As activity slowly keeps declining, lava flows continue to advance towards the sea in the Las Hoyas area, which fell over the cliff towards the foreland in the morning of December 11. The eruption continues with little changes in the coming days, until suddenly and without a marked and gradual decrease of the explosivity and lava outpour, the activity practically ceased with one large final explosion of Vulcanian type on December 12 at 12:00 UTC, producing a steam and ash plume that quickly rose to an estimated 5-6 km in altitude. This is due to conduits gradually closing up with debris in their upper parts as supply of rising material is less abundant, creating a plug which is suddenly thrown out when gas pressure underneath overcomes a threshold. As the volcano entered its final waning stage on December 13—now on its 85th day of activity—it became the longest eruption in recorded history on La Palma. On December 13, the eruption gained in intensity, both explosive and effusive. Phases of strong ash emissions and lava fountains alternated with calm periods with only steam emanating from the craters. Activity finally ceased at 22:22 UTC that same day. Subsequently, the entire eruptive area will suffer a period of slow degasification, gradually becoming weaker in the following 2 or 3 years. After this period, all volcanic manifestations will cease.
Observed phenomena
Cumulonimbus flammagenitus
The cumulonimbus flammagenitus cloud (CbFg), also known as the pyrocumulonimbus cloud (pyroCb), is a type of cumulonimbus cloud that forms above a source of heat, such as a volcanic eruption It is the most extreme manifestation of a flammagenitus cloud. The CbFg is a fire-aided or –caused convective cloud, like a flammagenitus, but with considerable vertical development. The CbFg reaches the upper troposphere or even lower stratosphere and may involve precipitation (although usually light), hail, lightning, extreme low-level winds, and in some cases even tornadoes. The maximum height was achieved during the Vulcanian explosion of December 13.
Volcanic lightning
Volcanic lightning is an electrical discharge caused by a volcanic eruption rather than from an ordinary thunderstorm. Volcanic lightning arises from colliding, fragmenting particles of volcanic ash (and sometimes ice), which release ions and generate static electricity within the volcanic plume, leading to the name dirty thunderstorm. Moist convection and ice formation also drive the eruption plume dynamics and can trigger volcanic lightning. But unlike ordinary thunderstorms, volcanic lightning can also occur before any ice crystals have formed in the ash cloud.
As Pliny the Younger described it in 79 AD upon seeing the eruption of Mount Vesuvius, "There was a most intense darkness rendered more appalling by the fitful gleam of torches at intervals obscured by the transient blaze of lightning."
Volcanic lightning over La Palma's Cumbre Vieja volcano eruption was first observed on October 11.
Dust devils
Volcanic whirlwinds or dust devils (Spanish: "tolvanera, diablo de polvo") have been seen twirling near the volcano, towering above the lava flow. Dust devils are strong and relatively short-lived whirlwinds. They form when a pocket of hot air near the surface rises quickly through cooler air above it, forming an updraft. In ideal conditions, the updraft may begin to rotate. As the air rapidly rises, the column of hot air is stretched vertically, thereby moving mass closer to the axis of rotation, which causes intensification of the spinning effect by conservation of angular momentum. The secondary flow in the dust devil causes other hot air to speed horizontally inward to the bottom of the newly forming vortex. As more hot air rushes in toward the developing vortex to replace the air that is rising, the spinning effect becomes further intensified and self-sustaining.
Elemental sulfur
On November 5 in the afternoon, deposits of elemental sulfur appeared for the first time on the main cone, indicating a clear change in its dynamics.
Restingolite
The eruption has emitted intriguing eruption products. These specimens appeared as volcanic "bombs" that are termed "restingolites" (after the village of La Restinga on the nearby island of El Hierro where the submarine eruption of Tagoro took place in October 2011) and exhibit cores of white and porous pumice-like material with buoyant capacity. Currently the nature and origin of these white stones is vigorously debated among researchers, with important implications for the interpretation of the hazard potential of the ongoing eruption. The "restingolites" have been proposed to be either:
Juvenile high-silica magma (e.g. rhyolite)
Remelted magmatic material (trachyte)
Altered volcanic rock
Reheated hyaloclastites or zeolite
Reheated xenoliths from pre-island sedimentary rocks
Based on their high silica content, the lack of igneous trace element signatures, and the presence of remnant quartz crystals, jasper fragments and carbonate relicts, the likeliest possibility is that "restingolites" are in fact xenoliths from pre-island sedimentary rocks that were picked up and heated by the ascending magma causing them to partially melt and vesiculate.
The oceanic crust beneath the Canary Islands dates from the Jurassic period (201.3 ± 0.2 – ~145.0 Ma). Therefore, ever since its formation, a great amount of sediments have been deposited, and the islands have grown over them. When magma rises from the mantle, it is capable of dragging rock fragments along its path. El magma cuando asciende desde el manto, es capaz de arrastrar fragmentos de rocas en su camino. As in El Hierro, fragments of these sedimentary pre-island rocks were expelled to the exterior. On occasions, magma assimilates part of these rocks.
They hence represent messengers from depth that help us to understand the interaction between ascending magma and crustal lithologies in the Canary Islands as well as in similar Atlantic islands that rest on sediment-covered ocean crust (e.g. Cape Verdes, Azores). The occurrence of these "restingolites" does therefore not indicate the presence of an explosive high-silica magma that is involved in the ongoing eruption.
Blue lava, blue fire, sulfur fire or Api Biru
Blue lava is a phenomenon that occurs when sulfur burns. It is an electric-blue flame that has the illusory appearance of lava. Despite the name, the phenomenon is actually a sulfuric fire that resembles the appearance of lava, rather than actual lava from a volcanic eruption.
Fumarolic circles
On the slopes nearest to the main cone, several large fissures have appeared with concentric circular shapes. These curious figures are produced due to fumaroles emanating through external cracks. Because of the emission of high-temperature gases and condensation, tephra is weighed down and is not carried away by the wind, which leaves behind these concentric circles on the surface.
Etymology
Volcano vents on La Palma have traditionally been either given Benahoarite names or, more rarely and not in recent times, named after the Saint on whose feast day the eruption began. An early proposal for a Benahoarite name for the new vent was Jedey, after a nearby village, but this was not received favourably. Others have suggested the name Tacande, which is actually already synonymous to Montaña Quemada. The name that was ultimately chosen is Tajogaite, a name that had gained wider support, as well as the name given to the region of La Palma where the eruption took place—Hoya de Tajogaite—located immediately to the west of the main cone.
Contrary to popular belief, the term tajogaite does not mean Montaña Rajada, which is a small mount located to the south of Llano de Tajogaite. The name is of Benahoarite origin, and it is derived from Tagojaite through metathesis. The toponym appears frequently from the 18th century onwards in local registers related to land property. It appears along with the variants of Tagojaite and Taguajaite, and it may be related to the Bimbape terms Tejeguate and Tejegüete from the neighbouring island of El Hierro.
The morphology of the term is typically Berber (Tamaziɣt), corresponding to the model t-t with the paragogic -e. The lexical elements are yet to be identified with certainty, but seem to occur as doublets in other placenames of the island. The term gaite is found also in Tenerife, with the meaning of 'fern root flour dough'. Tagoja, on the other hand, is a term that occurs in La Palma at the Tagoja Mountain in Santa Cruz de La Palma and Fuente de Tagoja at Gallegos in Barlovento, both being places that possess sandy soils which constitute ideal places for ferns to grow, just like Tajogaite. It could therefore be hypothesized that tagoja refers to the fern of which root has traditionally been used to elaborate 'gofio', 'gaites de tofe' (dough made from scalded gofio) and 'gaites de haran' (fern root flour dough)—namely the eagle fern (Pteridium aquilinum), which in fact is very abundant in the area of Tajogaite, Tagoja Mountain and Fuente de Tagoja.
As for the possible Bimbape cognates, Tejeguate, Tejegüete and related terms, they are thought to be composed of the roots h-w and h-w-g-h, which are shared by all existing Berber dialects with many examples in toponyms throughout Northern Africa (Morocco, Algeria, Niger, Mali, etc.), with the meaning of 'the color red'. If this is correct, Tejeguate and Tejegüete would be chromatoponyms characterised by the red color of their soil. In the case of Tejegüete in El Hierro, it is explained by the abundance of red ochre that, when moistened, forms an impermeable layer that allowed the construction of water reservoirs that guaranteed water supply to the locals of El Hierro for centuries. The dark reddish color of Tejeguate on the other hand, which is located in the lower part of the Golfo of El Hierro, is represented by its lava flows.
Yet another alternative hypothesis suggests it is related to the Berber tighiwit, which meaning is 'plowed field'.
Lastly, it is also hypothesised that Tajogaite is derived from tagogayt, referring to an unidentified perennial plant, due to its similarity with the Berber term teguq(te).
External links
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