La Palma's Cumbre Vieja volcano eruption of 2021
November 4
The eruption continues with no significant changes in observed and measured parameters. At the cone, several vents remain active with near-continuous pulsating ash-rich lava fountains, as well as intermittent stronger explosions, generating an ash plume rising approx. 2 km today. Most of the erupted lava is directly entering the lava tube system from the lower vents. Volcanic tremor has increased again compared to yesterday, but still remains lower than the average of the past weeks. Whether its amplitude corresponds to the lava output rate is in parts speculation; visually, the latter seems to be reduced at the moment. The lava flows did not advance significantly over the past 24 hours, with nearly all activity occurring along the southern margins of the active flow field. Trade winds today are carrying the ash plume, approximately 2 km high, towards the SW over the ocean, which is good for the airport on the east side to be operational.
Ash fall in the Aridane valley is increasingly a problem. More army personnel is called in to help remove the heavy load from roof and the streets before rains set in and make it much worse, as it will then form a natural cement-like mixture and increase its weight.
November 5
Overall activity—the eruption at the vent, the lava flows and internal seismic activity—has been lower. Ash emissions are intermittently intense, and the ash plume reached 2.4 km in altitude. The lava flows remain active, and they have so far covered an area of nearly 10 km² and destroyed 2,581 houses. It might appear as if the peak of the eruption is over and that it has entered a phase of slowly dying down, but tremor remains significant and even has been increasing again. Additionally, ground deformation has once again been showing a trend of uplift, now approximately 13-14 cm, suggesting that more magma is being stored at depth than what is being erupted. Sulphur dioxide (SO₂) and carbon dioxide (CO₂) emissions have risen also, to 29,000 tons per day and 1,850 tons per day, respectively. This increase fits with the model of more magma arriving at depth.
Moreover, elemental sulphur has appeared on the cone for the first time, pointing towards a clear change in the dynamic of the eruption. A reaction of hydrogen sulphide (H₂S) to form sulphur would entail that the magmatic component of the gas is decreasing whereas the emissions of H₂S are increasing.
November 8
The activity at the vents continues to gradually decrease visually and audibly. Less explosions have occurred and degassing noises are becoming less intense. Explosions at the vent are intermittent and no longer as vigorous as before, ash emissions, however, seem to have picked up. Lava emission continues, but likewise less vigorously. Some lava flows on the lower flanks of the cone, overlapping older flows. Volcanic tremor has remained at similar levels have plateaued, but generally continues to decrease. Hopes are emerging that the eruption may be coming to an end, but this is still too early to be certain of. A pair of two quakes with magnitudes 4.5 and 4.6 occurred last afternoon at 5.07 pm at approximately 38 km depth within 10 seconds from each other, but so far, there seems not to be any significant change in eruption intensity that clearly correlates. It is not known what the exact significance of these and other quakes is at the moment. Whether it is caused by an injection of new magma at depth, or gravitational adjustments perhaps caused by the depletion of magma from there or other reasons, is speculation.
November 9
The eruption undergoes few changes. Intermittent ash-rich lava fountains and strombolian-type explosions produce steam and ash plumes that continue to rise to 2.4 km in altitude, which drift southwest over the Atlantic. Lava effusion remains significant, likely at similar levels as during the past days, because the volcanic tremor signal and deformation data show no significant changes. It may not seem as abundant mainly because most of the lava erupted at the vents is flowing directly into a tube system and feeds various parts of the flow field, both by inflating it and creating new surface flows or outbreaks, on top of existing flows or as new outbreaks detaching from its margins.
While the latter lava flow activity has been less frequent in the past days and made for hopes the eruption might be exhausted, it has changed today: a new flow front detached from the southwestern margin and reached the beach of Los Guirres, south of the existing older sea delta, at 10.50 am local time. Fortunately, the lava flowing into the sea is at least not damaging so-far untouched land.
November 10—12
The number of quakes under the island has increased significantly again during the latest 24 hours, in particular the occurrence of quakes in the deeper layer around 35 km, where two shocks of magnitudes 4.2 and 4.8 were recorded on November 10, at 11:10 am and 1:23 pm, respectively. Additionally, two quakes of magnitudes 5.0 and 4.1 were registered on November 11 and November 12, respectively. All quakes were felt widely on the whole island, being several of the strongest in the current seismic and volcanic crisis. As to their meaning, it can only be speculated upon whether they signify a potential re-supply of magma at depth or perhaps the opposite, i.e. internal adjustments after magma has left storage areas below. A better interpretation of these events is likely only to follow after more time has passed. In the meanwhile, volcanic tremor continues to follow its slowly decreasing trend as yesterday and is low when compared to previous weeks, but still significant, in tandem with continued lava effusion that resulted in the spectacular lava flows falling over the sea cliff today.
All the observable data shows that the deepest part of the system that feeds the volcano is becoming less active and has less capacity to provide magma and feed the eruption for more time. These indicators include the falling levels of sulphur dioxide and the drop in seismic activity. Sulphur dioxide emissions, however, still remain high, with between 16,600 and 23,100 tons emitted a day, and more time must pass before the downward trend can be confirmed.
November 13
Activity continues with no significant changes, with similar intensity as during the past days, while on a very gradually decreasing trajectory. The eruption is now mainly effusive, producing lava flows. At the vents, explosive activity has been only intermittent and comparably weak recently, although still able to produce plumes rising to up to 2-3 km during phases of more intense activity such as this morning. Most of the time, however, only dense steam plumes rise from the craters, while fluid, degassed magma continues to arrive and flow through a tube system to arrive at the new active sea entry, where a second delta is now growing and has largely destroyed the beach of Los Guirres.
Volcanic tremor is stable, at similar levels as during the past days with some increase overall today. Seismic activity has calmed down a lot, with only 10 quakes above magnitude 3 recorded in 24 hours. However, these include a strong quake of magnitude 5.0 occurred this morning shortly before 7 a.m., again in the deeper layer at 38 km depth. Ground deformation continues to show a weak trend of deflation. All in all, the eruption does not seem to be ending soon, but likely is in its long tailing-off phase.
The eruption claimed its first life. A 72-year old man was killed while cleaning his roof from the heavy load of ash when the roof collapsed. He had a special permit to enter the restricted area to look after his home.
November 18
Nature has willed for the Cumbre Vieja volcano to remain active on the day that is half a century since the end of its forelast eruption, the Teneguía, which lasted 24 days, from October 26 to November 18, 1971. The Cumbre Vieja continues to rumble 60 days after it first started erupting on September 19.
The increasing trend of activity at the volcano ended suddenly last night, when volcanic tremor abruptly fell to lower levels comparable to those before the surge of activity in the past two days. In tandem with the volcanic tremor (believed to correlate with magma supply rates), visible lava activity has been significantly lower today as well. Less lava was visible at the surface and the active fronts advanced less than had been feared. Still, another 12 hectares of new land have been covered, mostly banana plantations, by the active flow (labelled #4 on official maps) that has been advancing between the cinder cones Montañas de Todoque and La Laguna, and was about 300 m from the sea earlier today. Despite the falling tremor, explosive activity has been quite intense today, with phases of near-continuous lava fountains and strong ash emissions generating a plume that rose to over 3,000 m altitude and drifted in easterly and southeasterly directions.
Reported gas emissions have increased again, to very high values of 16,000-32,000 tons of SO₂ per day, mainly directly from the vents, and 2,300-2,500 tons of CO₂, mainly in the form of diffuse emissions from the soil. In the beginning of the eruption, up to 50,000 tons of SO₂ were injected into the atmosphere per day. Deformation of the ground continues to show a slow trend of deflation. Earthquakes decreased also by about 70% in intensity and numbers compared to yesterday. During the past 24 hours, there were 3 quakes of magnitudes 4.3-4.6 as well as 33 quakes between 3.0-3.9 (while there were more than 100 yesterday). Overall, the eruption continues to follow a very slowly declining trend, but seems far from over.
November 19 — 20
The eruption has shifted most of the visible activity to the area close to the vents again. Like yesterday, there were continuous low lava fountains with dense ash emissions, producing a plume reaching 3,500 m altitude, as well as a new significant lava overflow from the vents. The ash and steam plume reached 3,500 m height today. It seems that sections of the northern crater wall in the cone collapsed, allowing contained lava to surge out in a short flood, or that generally, more lava is arriving at the rims and able to overflow them. As in the previous cases this happened during the past weeks, a new voluminous lava flow traveled downhill from the cone and invaded new areas, destroying more buildings in its path.
It is not known or easy to say what exactly causes such lava surges. It could be the result of a temporary increase in magma supply or actually also be caused by a decrease of the amount of lava going into the tube system, possibly caused by some obstacles or blockages, forcing some of it to erupt onto the surface at the vent is unknown. Volcanic tremor remains similar as yesterday, but inflation has again increased a bit and totals around 9 cm compared to pre-eruption levels at the station closest to the eruption, which suggests that new magma has been accumulating beneath the surface (and yet has to come out).
On November 19, a magnitude 5.1 quake at 01:08 am, the largest earthquake since the eruption began, woke up the island. The numbers of quakes remained relatively low, with 10 quakes in total of magnitudes ranging from 3.0-4.0. This however changed on November 22, with 51 earhquakes in total. The strongest one being of magnitude 4.8 at 36 km depth, as well as a deep 2.7 magnitude quake at 45 km depth.
Sulfur dioxide emissions increased to high values of around 24,000 tons per day. Along with the continued inflation and perhaps the occurrence of strong quakes in the magnitude 4-5 range might indicate that more magma is able to erupt in the near future.
On November 20, the scientific committee of the Canary Islands Volcanic Emergency Plan (Pevolca) raised the rating from VEI 2 to VEI 3, based on the 10 million m³ of ejected tephra measure.
November 22
Lava flow number 7 reached the sea to the north of the first lava delta on November 22, closer to the port of Tazacorte. As of now, there are three lava deltas including this one.
November 26
The activity remains elevated. After yesterday's surges of lava from a new fissure system south of the cone, lava fountains returned to the main vents at the cone, first in form of a round dome-shaped fountain of very liquid lava from the lower vent, and later as a taller, more gas-rich jetting fountain from the summit vent which had been very active especially in the early phase of the eruption. The latter activity has continued throughout a very stormy and rainy night and into this morning, then decreased a bit although it still produces fountains. The generated ash plumes rose to up to 3,500 m altitude and drifted east where it continues to disable the airport, now closed for 6 or 7 days in a row. Many airlines have canceled flights to La Palma altogether for the whole time up to spring next year due to the uncertainty whether the airport is operational or not, and whether they can actually fill seats. Requests to travel to the island likely have dropped massively, further damaging its economy that already suffered a very hard blow from the eruption.
Seismic activity overall remains low and comparable to the past days. The National Geographic Institute (IGN) reported a total of 44 earthquakes in its latest 24-hour reporting period. 5 of them were felt by the population and the strongest one was last night's magnitude 4.8 quake at 10:40 pm with a depth of 37 km. The seismicity continues under the central area of Cumbre Vieja volcano in the same areas as before. Most of the latest recorded earthquakes are located at depths 10-15 km and only 7 of them at depths greater than 30 km. The amplitude of the volcanic tremor signal continues to be low, but with very significant upwards spikes corresponding to the increased lava effusion phases, one likely in progress as there is a new tall spike visible. Inflation has restarted at the LP3 station closest to the vents. Likely, this means another pulse of magma underway, which (as a speculation) could be in relationship with last night's magnitude 4.8 quake. In the other stations, the slight deflation possibly related to deep seismicity has stabilized, IGN reported. Sulfur dioxide (SO2) emissions were at 5,250 tons per day. The current height of the cone was measured at 1,126 m above sea level, but it's likely to continue to grow even more with time.
November 28
Several new vents opened this morning 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. This comes as a result of a new surge of magma that announced itself as underway by the recently observed inflation during yesterday and the previous day. Instead of erupting through the existing vents at the cone, like on Thursday, the magma chose to create new vents nearby - likely, the older conduits at the cone have become too high and too "difficult" to reach compared to creating new fissures at the base of the cone. Sulphur dioxide emissions also have once again peaked with a rate of 30,000 to 50,000 tons a day.
The lava flows from the new vents have quickly crossed the Tacande road and are enlarging the northern margin of the flow field, covering new so-far untouched land in that part. The ongoing eruption is already counting as the largest on La Palma Island in over 500 years. It has likely overtaken the 1585 eruption at Tahuya as the largest by volume eruption on the island in recorded history. The latter erupted approx. 300 million cubic meters (or 0.3 cu km) of lava, while the exact volume of the current and still ongoing eruption is estimated to be at about this value already.
Along with the new vents allowing magma to quickly rise through a new (and compared to the older vents likely "easier") path, volcanic tremor has jumped up significantly this morning.
At the same time, the inflation from the past days has been neutralized by an almost equal deflation signal - this suggests that the extra amount of magma stored recently has been erupted during the ongoing surge of activity that began this morning. How long it will last will be shown in the near future.
The opening of the vents was not accompanied by significantly changed seismic activity, which indicates that the magma needed little energy to break through the ground at nearby locations as before. Earthquakes have increased marginally in numbers, but not in energy during the past 24 hours. The National Geographic Institute recorded 91 events of magnitudes up to 3.5.
The activity at the old and new vents produces dense ash plumes, rising to 1,600 m above sea level and drifting southwest over the Atlantic Ocean (and sparing the airport on the east coast).
As to the other lava flows, activity continues to feed them as well: according to the latest official summary of the situation, the flows labelled #7, #4-5 and #1-9, as well as #10, which has merged with #11 further south, but stopped its advance. Various active fronts are fed by the tube system, most notably in the area near Laguna Hill. The total area covered by lava flows, including the lava deltas, stands at 1,151 hectares.
The new lava flow from the fissure on the northern side of the cone have already reached a length of a few kilometers and their fronts have reached the area of La Laguna as well as Dos Pinos.
November 29
The eruption continues at elevated levels with low lava fountaining and abundant lava flow emission from the new vents that opened yesterday morning around the northern base of the cone. Associated ash emissions have been rising to 1,400 m altitude and drifting south-southwest over the sea. The new lava flows follow a route around the northwestern side of the cone and have been advancing quickly north of the existing flow field, on their path invading new land and destroying additional structures. So far, 2,695 building have fallen victim to the lava flows since the start of the eruption.
The most northerly of the active flows has come dangerously close to the main LP-3 road junction in Tajuya, which is the principal artery for traffic to connect the Aridane Valley with El Paso.
Volcanic tremor has dropped from its steep peak, but remains elevated when compared to the situation before the new vents opened, likely in tandem with ongoing high lava effusion rates.
November 30
Abundant lava effusion as well as mild fountaining and ash emissions from the new vents around the northern feet of the cone continue at similar levels as the day before. Volcanic tremor fluctuates strongly around moderate levels, while seismic activity is picking up and overall deflation of the ground continues, which points to rapid discharge of stored magma. Lava flows advanced into so-far untouched parts of the industrial area of Los Llanos.
Seismic activity reached a record number of 374 quakes of magnitudes above 2 during a 24 hour window on November 30. Volcanic tremor has increased and continues to fluctuate strongly. While internal activity is high, the visible activity has decreased a bit since yesterday. According to official statement, there are now "moments" with no (or almost no) activity at the vents. These alternate with phases of frequent and loud explosions, sometimes accompanied by short-lived lava fountains and ash emissions. The lava flows that had been spectacularly active in the past days continue to be visible near the vents, but were much less so in the past 12 hours. It might be that some of this apparent decrease is due to the fact that most lava is flowing inside the tunnels, but on the other hand, there has been very little advance at the fronts, most of which seem to be cooling now. According to the latest data, the area covered by lava flows stands at 1,134 hectares, out of which 43.46 ha are at the southern and 5.05 ha at the northern lava delta. The lava flow field has a maximum with of 3,350 meters. As seen multiple times in the past weeks, the apparent (at least relative) calm of visible activity can change very quickly, and is likely no indication that the eruption is close to an end.