El Hierro eruption (continued – 2)
Update 6pm: After an afternoon of large quakes, the biggest one yet. Direct reports from El Hierro say it occurred at 5.01pm, and really shook property. This quake is being recorded as 4.7 on the Richter scale, but direct reports say it felt bigger than that. It was also felt on La Palma.
Update 11.30am: Scientists say that the energy released since the start of this latest crisis has exceeded the total energy released during the initial part of the eruption throughout 2011. So far today, there have been 51 earthquakes over Richter 3, eight of them over R4. Naturally the public has felt the tremors. The strongest ones have also been felt on other islands.
Update 29 March: There were brief power failures in the west of El Hierro last night, with 64 earthquakes overnight: experts say that there are now so many quakes that IGN is now only listing the stronger ones, so the real number must be in the hundreds. The strongest so far (already) today is a 4.3, and deformation continues to increase which is thought itself now to be causing a separate series of tremors to that of the magma-based quakes under the sea. As at now, 9.30 am, there are said to be strong quakes at a high rate.
Update 11pm: Yet more calm followed by activity, and a calm-ish evening followed in the last hour and a half, by 10 earthquakes of Richter 3+, the strongest of which was 4.1. There have been 188 earthquakes today … so far.
Update 1.30pm: The emergency services have just released the above image of the area currently affected by the yellow alert.
Update noon: Involcan has released carbon dioxide readings, which are said to be greatly in excess of normal levels. Some 1,684 ± 72 tons of CO2 per day are currently being released from below El Hierro, a level even stronger than the first and second phases of the eruption last year.
Update 11.30am: Between 9.15 and 11am there were 15 earthquakes over 2 on the Richter scale, 13 indeed of them being over Richter 3, thez strongest being 3.8. At 11 on the dot, a 4.1 was registered.
Update 28 March: Calm, followed by a series of strong earthquakes around 5.30am, followed by a calm spell, and then another series of strong earthquakes from around 8am. That’s been the pattern overnight and this morning, many of them over 3 on the Richter scale. Experts say that if these had occurred under land the island would be ringing like a bell. As it is, they are slightly out to sea off the south western tip of the island. I have little doubt that there will be further updates throughout today.
Update 9pm: Pevolca has issued a yellow alert for the area of Pozo de la Salud towards the south, and one lane of the Los Roquillos tunnel has been closed as a preventative measure. Also closed are the roads between Cruce de La Tabla and Sabinosa, and the access to Playa La Madera.
Update 6pm: There is another series of strong earthquakes shaking El Hierro at the moment, still to be classified by IGN.
Update 4.30pm: Experts say that there are spectacular earthquakes going on at the moment in the sea west of El Hierro. Another strong earthquake, 4.4 on the Richter scale, has been registered which made chairs and light fittings move and windows rattle. Like the 4.6 a little earlier, it too was felt on other islands.
Update 27 March: 195 quakes yesterday. Today, we have confirmation that the epicentres are moving back towards the island. At lunchtime today, experts were talking about a slightly quieter day, with about 60 or so quakes overnight and this morning at a depth of 12-15km, the strongest of which was 3.3 on the Richter scale. At 1pm, however, there was a series of Richter 3 tremors, with two around 1.30pm registering 3.7 and 3.9 at a depth of 15km, inevitably being felt by the public. At 3pm, another series of 11 R3+ earthquakes was registered in just an hour. Involcan has released the above photo of the rockfalls in the El Golfo area described yesterday.
edit: within minutes of posting the above, the strongest earthquake yet has been felt, 4.6 on the Richter scale at a depth of 19km. It was felt beyond the island, in La Palma and La Gomera and even on Tenerife, though experts say this is perfectly normal for such a size.
Update 26 March: There were 224 earthquakes yesterday, one of which as we know was 4.1 on the Richter scale, the strongest since the eruption first started. Pevolca met as planned today and have said that there is a strong chance of a 4.3+ earthquake, they think a 75% or so chance, but maintain there is no significant risk to the public, at least not sufficient to warrant extraordinary measures. Although today was slightly calmer, 170 quakes had been recorded by around 7pm, many being felt by the public for minutes at a time, and there were reports of windows vibrating and rockfalls. About an hour ago, at 10pm, however, some quite strong earthquakes were registered, and these are still ongoing as I post at just gone 11pm. The magnitudes have not yet been confirmed. From what information is actually available of this last series, it seems that these stronger quakes are moving southwards and towards the island.
Update 25 March: Yesterday’s total was 159 earthquakes over 2 on the Richter scale. Today, the biggest quake so far, of 4.1 at 2.41pm, again to the west and under the sea at a depth of 16 km. A further ten quakes over 3 on the Richter scale followed within the next hour, the largest of which was 3.7 at just past 3pm. Many quakes have now been registered today over Richter 3, a clutch of eighteen of them between 3 and 3.9 started the day off around 1am. Accompanying these is a strong upward deformation, which is said to be sufficient to cause some cracks to appear in buildings and infrastructure.
The PEVOLCA committee of insular and regional authorities and scientists is to meet tomorrow to discuss the current crisis. At present they are saying there is no risk to the public, but they will be investigating potential scenarios which might arise in the near future. Experts say that today represents the strongest volcanic activity since the whole eruption started in 2011. The graphic above shows the location of the activity over the past three days.
Update 24 March 10pm: As of now, there have been 148 earthquakes today, those over 3 on the Richter scale being felt by the public. Involcan is sending scientists to the island tomorrow to carry out measurements and oversee analysis systems.
Update 24 March: Yesterday’s count ended up at 164, the busiest day so far in this swarm by some way. Overnight there were a further 62 tremors over 2 on the Richter scale, hundreds of smaller ones, now getting slightly deeper again back to the 16 -17km depth and moving slightly out to sea off the western tip of the island. The deformation is what is really spectacular, however, according to expert vulcanologists: the west of the island has been forced 2 cm upwards in the last 24 hours alone.
Update 23 March: There were 93 earthquakes yesterday, but today saw 134 up to 7pm, the strongest activity since the start of this swarm. They are gradually getting shallower, into a depth of around 12-14 km, which suggests, experts say, that magma is reaching higher levels. Several have been over 3 on the Richter scale.
Update 22 March: There was a spurt of activity last night culminating in a quake of 3.8 on the Richter scale, the strongest so far this year. It was on the western tip of the island at a depth of 18km, and was felt by the public. The deformation also continues. Experts say that the idea that this swarm was dying away may have to be revised. In all, there were 117 tremors yesterday. There have been around 50 today, though that figure will be confirmed tomorrow: all have been around the western tip, with the most powerful registering 2.9 at a depth of 14 km.
Update 21 March: Experts say that this swarm is dying down now, with just 24 tremors yesterday. Their readings show magma at a depth of 16 to 18 km reaching other channels in a way to the surface. The island’s deformation continues despite the tremors releasing pressure. Looks like we will now have to wait for the next swarm to give a few more hints of developments.
Update 20 March: As the experts have said before, the magma is looking for a way out, and is choosing new routes every time its path is frustrated. As such, one of the more interesting elements of these tremor swarms is the way the quakes “migrate”: the pattern of movement shows very clearly the new path that the magma is tracing. Now it is clear that the current swarm is moving towards the unpopulated west spur of the island. This swarm of tremors, however, marking a new magma intrusion, seems to be slowing down. Perhaps this path too is blocked. Only time will tell where the magma will try next. One thing seems certain, though, and that is that we have not heard the last of this “eruption”.
Update 19 March: Yesterday’s tally was 143 earthquakes. Today, already by 8am, there had been 24 registered (the registration ignores the minor tremors), the strongest of which was 3.1 on the Richter scale at a depth of between 16 and 18 km. These are occurring under land, though some are in the Golfo area under the sea, as the above graphic from yesterday shows.
Update 10pm: There have been around thirty more tremors this evening since my earlier post, most between 1.8 and 2.7 on the Richter scale. The above diagram shows the distribution. Experts say that this latest swarm is showing new magma intrusion between around 16 to 25 km. As they have said before, “something interesting is happening”.
18 March: IGN’s volcanic measurement network has registered a new clutch of seismic activity in El Hierro today with a total of 28 tremors of between 1.9 and 2.6 degrees on the Richter scale. None were felt by the public. The largest of the quakes, 2.6, occurred at 2.29pm to the west of Frontera, under land, at a depth of 20 km. It was followed at 2.42pm by a 1.9 tremor at a depth of just 2km to the north west of Frontera. The rest of the seismic activity was mainly to the northwest of the municipality and to the southwest of El Pinar. There were three quakes yesterday too, the largest of 3.8 degrees on the Richter scale to the west of Frontera, again under land, at a depth of 13 km. IGN says that there have been 30-odd tremors over the last several hours.
Update 31 January: After a few days of clustered tremors, there was just one today, but it was strong for this series, at 2.9 on the Richter scale. The earthquake occurred just before 4.30 at a depth of 15km: its epicentre was located off La Restinga on the turqouise patch. Experts say that the harmonic tremor graphs show changes too, and that the episode suggests that something “interesting” is happening.
Update 20 January: A football-field sized turquoise-coloured patch has appeared off the south coast of El Hierro. IGN says that this is a periodic degassing associated with the eruptive process but does not necessarily indicate a resumption of volcanic activity. The President of the El Hierro Cabildo, Alpidio Armas, has called for calm, and reminded the public that this is not the first time that such patches have been seen in the area.
Update 2 January: Since the 31st’s update, there have been one or two lulls, but generally there are tens of these quakes each day now, all at a depth of between 15 and 20 km or so, and up to a maximum of around 2.5 on the Richter scale, with a general albeit slight increase in strength. What marks this swarm out as interesting is that they’re centred on the hitherto less affected north El Golfo region. Yesterday saw quite a strong harmonic tremor, which has almost died away today; experts say that this suggests magma is trying to find a way out and has currently been halted. Only time will tell how and where it will make itself felt next.
Update 31 December: Today has been a very busy day for seismic activity, with 20 earthquakes today in the El Golfo region of magnitudes ranging between 1.5 and 2.5 on the Richter scale. 2012 is ending with a clear swarm, as El Hierro shows that it will almost certainly have more in store during 2013.
Update 15 December: It’s been rumbling away for the last few days, with a 2.6 tremor on Thursday 13th which was felt by the public. Experts say this set generally is showing the same patterns as in the last swarm.
Update 11 December: As I said in my last post on this on 18 September, “it’s incredible how quickly these phenomena can rise and die away … it shows the pattern for the future”. And now we have another swarm, with eleven tremors recorded over the last 24 horus under the centre of El Hierro, all moving southwards. None were over 1.8 on the Richter scale. It will become clear over the next day or so whether this builds up into another eruptive stage, or dies away as quickly as the last flurry.
Update 18 September: It’s incredible how quickly these phenomena can rise and die away. It seems that this swarm is already dying away, but it shows the pattern for the future, it seems: this is an eruption that will happen at some point. It appears that the magma seeking release from beneath El Hierro is finding two routes of escape, the first in the El Golfo bay region, and the other directly under the island land mass, which of course is the crater part of the old volcano itself. There have been three quake swarms so far, the first one resulting in the eruption in the Las Calmas sea south of La Restinga , the second one was just in the form of tremors that had no surface phenomena, and now this short-lived third one which has seen a clear movement southwards. It will be back …
Update 17 September: Scientists from the Instituto Tecnológico y de Energías Renovables (ITER), which forms part of the Instituto Volcanológico de Canarias (Involcan), have cofirmed from the deformation in El Hierro that the eruption has reactivated. Between 13 and 16 September there has been an horizontal displacement northwards of 1.62cm and a vertical displacement of 2.9cm. Yesterday’s tremor count ended up at 197; today’s was slightly lower, at 105 as of 9pm.
Update 16 September 9pm: As of 9pm, there have been 185 earthquakes today, and IGN says they are still slowly migrating south, still all under land.
Update 16 September: Yesterday’s tally in the end was 167 earthquakes, and just between midnight and 7.30 this morning 73 have been recorded, the largest so far today being 2.7 on the Richter scale. Deformations are also increased, northwards around 1.5cm and 2cm vertically.
Update 15 September: 110 earthquakes recorded up to late afternoon, one of them early this afternoon registered as 3.2 on the Richter scale which was felt by the public. All of them were under land, beneath the original old crater.
Update 14 September: It’s been rumbling away on and off for the past six or so weeks, the activity has never completely died away, but today there has been quite a swarm, with 61 earthquakes being registered. One oddity is that they appear to have been at two distinct depths, with shallow weak tremors in the El Golfo bay region, and deeper strong tremors moving south throughout the day and completely under land. Some experts think that this indicates that magma could be moving under the island. IGN has a whole section of pages for the El Hierro eruption process HERE.
Update 6 August: PEVOLCA has now put El Hierro back onto green status, after little activity since 16 July. The alert is over – this time.
Update 19 July: There have no earth tremors at all since yesterday morning and experts think the current swarm is therefore over. No doubt this will continue to bubble up periodically now until a proper eruption takes place – who knows when.
Update 10 July: “It could carry on like this for a year, it could disappear completely, or we could have an eruption”. That’s the expert view in a situation where all possibilities remain open two weeks after a new magmatic intrusion resurrected seismic activity in El Hierro, a period in which more than 300 earthquakes have been strong enough to be felt by the public. The current situation seems to be periods of calm punctuated every day or so by one or two clusters of strong tremors.
Update 8 July: After a relatively quiet few days, another earthquake cluster started around 9.30 this morning. Several have been felt by the public, and one, still to be finally calibrated by IGN, is thought to be in the region of Richter 4. The deformation is now 10cm.
Update 4 July 4.30pm: The GES helicopter flew over the area this morning and scientists from Involcan, with a thermal camera, and from IGN, say they have not observed anomalous parameters in the region where the jacuzzi reappeared yesterday. They say this means there are no significant changes in the active magmatic process, though they will be carrying out continuous analysis.
Update 4 July: And now the jacuzzi is back, spotted last evening by an emergency Search and Rescue helicopter. It is some 180m from the coast – Pevolca gives coordinates 27º 4.573 North and 18º03.761 West, and issuing a white mark which is still being analysed. The helicopter should be flying over the scene again as I type (11.30am), equipped with a thermic camera to see if it is an eruptive focal point.
Update 3 July 4pm: Pevolca says that over the coming week further earthquakes in the region of Richter 4.4 are likely, perhaps even reaching 4.5 or 4.6. The pressure of magma has now made the deformation grow to 9cm.
Update 3 July: It’s always the way. The press had just announced that yesterday’s seismicity was reducing when it suddenly stepped up a considerable gear! Last night, indeed, was not only the most active since the eruption restarted, but the most active since July 2011! A chain of tremors, felt throughout the island, among them one of 4.4 on the Richter scale. Between 9pm and midnight, there were 40 or so, 18 of which were over Richter 3. In many areas people left their houses in alarm – this was the case in Sabinosa, El Mocanal and La Restinga, and quakes were felt even in Valverde and Tamaduste, places which had been unaffected to date. Last night’s cluster was localized in the Faro de la Orchila and El Julan area. Pevolca is to meet urgently at midday to discuss the new level of activity.
Update 2 July: The deformation is now 7.5cm, a steady and rapid growth, says IGN and Pevolca (Plan de Protección Civil por Riesgo Volcánico). The eruptive process continues, and IGN data indicate the seismicity is localizing in “an extensive area, with greater dispersion and numerous epicentres in the sea”. This area is to the west of El Hierro, and includes the area of El Julan and the Las Calmas sea. Since last Sunday, over 1,250 tremors have been recorded, 165 of which have been greater than 2.7 on the Richter scale – one yesterday morning was another large one of 4, but there were several of 3+ too.
Update 30 June: IGN says that the deformation continues to grow, and at the same rate, and is now 6cm, with a centre of pressure in the Las Calmas sea, the site of the previous eruption. Seismic activity remains stable, though more concentrated, and localized slightly to the west of yesterday’s registered tremors, in El Julan and the Las Calmas sea. So far, since last Sunday, more than 1,100 tremors have been recorded, of which 144 have been over 2.7 on the Richter scale. Most have been at a depth of around 20km. The latest was another strong one, of 3.6 on the Richter scale, just before 10pm.
Update 28 June: The deformation is now 5cm, equal in just four days to the entire deformation during the previous eruptive process. The energy released is some 420 billion joules, which experts say shows a clear acceleration of the magmatic process. Pevolca says that there have now been more than 750 tremors since the process reactivated on Sunday.
Update 27 June 10pm: A tremor of 4 on the Richter scale was registered this evening at 7.55pm, large enough to be easily felt by the public in the Frontera/El Pinar area, and which set car alarms off in La Restinga. This is the strongest quake since the volcano reactivated. Today more than 160 tremors over 1.5 have been recorded.
Update 27 June: The Canarian Government, in collaboration with IGN (Instituto Geológico Nacional) and Involcan (Instituto Volcanológico de Canarias), has activated a yellow volcanic alert for the areas of El Julan and La Dehesa, unpopulated regions in the south and southwest of El Hierro. The yellow alert allows for information and the activation of vigilance resources for eruptive processes, said the director general de Seguridad y Emergencias del Gobierno de Canarias, Juan Manuel Santana, who explained that the decision was taken after detecting a significant increase of seismic movement and land deformation, said to have been created rapidly and increasing to 3cm since activity restarted three days ago (in the whole of the previous eruptive process the maximum deformation was 5cm). Experts say they don’t expect an eruption imminently, but confirmed there is magma movement – and that the eruption has reactivated.
Update 26 June 11.45pm: More and stronger – 165 tremors over 1.5 on the Richter scale were recorded today, and between 4.15 and 6pm, nine were registered between 3 and 3.5, several of which were felt by the public. All were located under the peak of El Hierro, and appeared to be moving southwards towards La Restinga, at a depth of between 17 and 23km. Geologists say that since the present quakes started at 9.30pm on Sunday evening, they have not stopped, which is how the last eruption started.
Update 26 June: 117 tremors since midnight is the count from El Hierro as at 1.30 this afternoon. Six have registered either 3 or 3.1 on the Richter scale: one at 2.41am, then two within a minute of each other at 4.10 and 4.11am, others followed at 8.40, 8.49 and 10.40am. All have been at a depth of between 18 and 20km.
Update 25 June: IGN has recorded more than 60 tremors in El Hierro since 9.30 last evening. Three of the stronger ones have been felt by the public, the largest was just after 9am this morning, of 3.8 on the Richter scale, at a depth of 19 km. Geologists are following the evolution of the situation in case a new eruption phase is about to start.
Update 19 June: IGN recorded another cluster of tremors between 6pm yesterday and 2.50 this afternoon. There were 16 in total, all between 1.6 and 2.3 degrees on the Richter scale and at a depth of between 15 and 19 km; 14 of them occurred within the space of two and a half hours, between 9.52 and half past midnight, and all but one were in the El Golfo region – the last one was northeast of Valverde. None were felt by the public.
Update 14 June: IGN registered eleven tremors between 4.30 am and 8am this morning in the general La Frontera area. They ranged between 1.7 and 2.8 on the Richter scale at a depth of between 20 and 24 km. It doesn’t appear that any of the activity was felt by the public.
Update 4 June: It’s back. The Frontera area had five tremors this morning, one of which was felt by the public. Within just 25 minutes between 07.18 and 07.43, the first four were registered between 1.6 and 2 on the Richter scale; the fifth was registered at 12.45 with a magnitude of 2.9 and an epicentre on the coast near to the Valle del Golfo. All occurred at a depth between 17 and 20 km, says IGN.
Actualidad Volcánica de Canarias (AVCAN), linked to the Asociación Vulcanológica de Canarias, has confirmed that the tremors indicate a magmatic origin and, naturally, a possible pressurization which, if it were to continue, would cause more seismic activity in the area.
Update 20 April: Finally, after weeks of calm, El Hierro’s eruption alert status has been returned to green. Pevolca and the Canarian Government have now removed the yellow alert, thereby confirming the return to normality … and the island’s survival after months and months of tension with the Las Calmas sea eruption. In the end, there was no new island, no new land mass, but El Hierro is the youngest Canarian island. Who knows what will happen in future weeks, months and years … or even decades. The yellow alert has, for the moment, been kept for the sea area around the volcanic cone.
Update 9 March: Capitanía Marítima de Santa Cruz de Tenerife has reduced the maritime exclusion zone to a radius of just half a mile around the volcano emission point south of La Restinga. The sector is defined as a circle drawn with its centre at latitude 27-37.18 N and longitude 017-59.58W – as per the map above. The decision was taken in the wake of Pevolca’s reduction of the alert level. In the newly reduced exclusion zone, all fishing and water sports, including diving, are banned. Any navigation within the zone must be with prior authorization from the Capitanía Marítima.
Update 6 March: The red alert for the Las Calmas sea area of the eruption has been reduced to yellow. The rest of the island remains on yellow alert. The restrictions on Arenas Blancas, Tacorón and Playa de Los Mozos will be relaxed as soon as a new document is released giving details of a reduced exclusion area. At the moment, the 4 mile maritime exclusion remains. Recommendations against swimming, fishing or scuba-diving remain in place until samples from the area’s water are analysed by Public Health services.
Update 5 March: The science committee says that the volcano, which started erupting on 10 October, has died. The decision to make the announcement was agreed unanimously by the experts. In what must have meaning for the scientists, if not for the public, they say that the “eruptive process continues” and that scientific vigilance will be maintained.
The volcano is now just 88 metres from the surface of the sea, well within the limits for a Surtseyan eruption which, it now appears, will not happen after all.
In the next few hours Pevolca will meet to decide what measures need to be left in place for public protection.
Update 29 February: There was an earthquake just after 5am yesterday morning with its epicenter east of La Restinga, i.e. between El Hierro and Tenerife. There is now a stain in the area, as shown in the map below, which suggests there might be another vent in this area.
Update 28 February: The main cone has been growing over recent weeks: as we saw on 14 February it was at a depth of 120 metres. The latest scans from the Ramon Margalef show that it is now at a depth of 100m. Since this is the point at which Surtseyan activity could take place, we could see some real action any time now if the eruption continues.
Update 23 February: Over the past week and a half, the harmonic tremor and surface activity have both been at very low levels, leading some to argue that the eruption is slowing down to an effective halt. At the same time, however, the number of earth tremors has been very high – there were 23 on Monday alone – and some have been strong or shallow enough to be felt by the public. Today, the activity is clear, with 7 tremors, and visible bubbling on the Las Calmas sea surface, and a heat haze above it, which vulcanologists say is caused by superheated steam warming the water column above the vent. Meanwhile, the science ship Ramon Margalef is carrying out further bathymetric scans to contribute to creating a detailed image of the sea bed.
Update 14 February: The Canarian Government has issued a statement that the eruption is still active, and constant vigilance is being maintained. Pevolca say that there are two cones: the first main one is at a depth of 120 metres and the second at a depth of 200 metres. The harmonic tremor is currently registering minor activity. The Tacaron coast which has been closed is now reopened.
Update 12 February: More mixed messages over the last couple of weeks, with the authorities saying the eruption is diminishing, and the science ships leaving the scene, but at the same time, a powerful bubbling has been visible with smoking lava stones and a huge stain, the harmonic tremor is up and down as usual, and there have been an increasing – and increasingly shallow – number of earthquakes. It could be about to go up or fizzle out, and no-one seems to know.
I have pruned this post because it was becoming too long and unwieldy. I have had to divide all previous posts into two sections: the earliest are now HERE, and the later ones, to the start of this post, HERE.