Earthquake Swarm (11000+) El Hierro, Canary Islands

maquiladora · 23-07-2011 6:41pm #1

There is currently a very large earthquake swarm happening in the Canary Islands, at El Hierro.

This pic shows the swarm at 368 but there is now over 400 and it's still going.

http://twitpic.com/5um4vi

I've only just stumbled on this in the Eruptions blog so I'm still trying to find some more links, live data etc.

This could well be the prelude to a volcanic eruption on the island.

As far as I know there is currently no indication that this activity could trigger a collapse/tsunami, but seemingly it has happened in the past :

Islands of volcanic origin, such as the Canaries, have an especially large potential for triggering a tsunami. That the Canaries constitute a danger was shown 300 000 years ago when a part of the island El Hierro slid into the sea, triggering a mega-tsunami which carried rocks as high as a house for many hundreds of metres into the interior of the east coast of what is today the USA.

http://www.tsunami-alarm-system.com/en/phenomenon-tsunami/occurrences-atlantic-ocean.html

Information of the Geology of El Hierro here : http://www.elhierro.com/geologia-en.html

Iancar29 · 23-07-2011 6:56pm

maquiladora wrote: »

There is currently a very large earthquake swarm happening in the Canary Islands, at El Hierro.

This pic shows the swarm at 368 but there is now over 400 and it's still going.

http://twitpic.com/5um4vi

I've only just stumbled on this in the Eruptions blog so I'm still trying to find some more links, live data etc.

This could well be the prelude to a volcanic eruption on the island.

As far as I know there is currently no indication that this activity could trigger a collapse/tsunami, but seemingly it has happened in the past :

http://www.tsunami-alarm-system.com/en/phenomenon-tsunami/occurrences-atlantic-ocean.html

How regular are such swarms for the Canarys?

Looks serious!

maquiladora · 23-07-2011 7:03pm

Iancar29 wrote: »

How regular are such swarms for the Canarys?

Looks serious!

As far as I know its the biggest swarm for anywhere in the Canary Islands for 40 years. Last time there was anything like was before Teneguía erupted in 1971, but that was on La Palma, so I think this is the biggest swarm that has ever been recorded at El Hierro.

No need to panic though, if there is an eruption it will probably be a small one, but it might look pretty!

cherryghost · 23-07-2011 7:06pm

Why isn't USGS picking up on any of this? Too small to be considered?

Well according to his twitter account the quakes are getting shallower and shallower

cherryghost · 23-07-2011 7:15pm

Here we go:

http://www.ign.es/ign/layoutIn/sismoListadoTerremotos.do?zona=1&cantidad_dias=10

maquiladora · 23-07-2011 7:15pm

cherryghost wrote: »

Why isn't USGS picking up on any of this? Too small to be considered?

Well according to his twitter account the quakes are getting shallower and shallower

Yeah I don't think USGS show small earthquakes for areas outside the US (guessing). I think the biggest quakes in this swarm are around 2.3, not very big, its the sheer number of them thats interesting.

ScouseMouse · 23-07-2011 7:21pm

I'm sitting here in Tenerife and there is nothing about it.

up for anything · 23-07-2011 7:28pm

GEOLOGY

The island of El Hierro is situated in the most southwestern extreme of the Canaries at 27.7º north and 18.0º west, and is the smallest of the archipelago at 278.5 km2.

El Hierro was designated by UNESCO as a Biosphere Reserve in the year 2000, with 60% of its territory protected to preserve its natural and cultural diversity.

It's no wonder that the smallest Canary Island delights all who visit, not only for its great natural and ecological attractions, but also for the contribution of its inhabitants in the sustainable development and conservation of the natural and hereditary wealth of the area.
The origins of the island date back some 100 million years when the ocean floor shifted with the movement of the earth's mantle. The crust consequently cracked into a three pointed star releasing flows of magma.

After three successive eruptions, and consequent accumulations, the island emerged from the ocean as an imposing triangular pyramid crowned by a volcano more than 2,000 metres high.

The initial crevices became channels for further lava flows which grew into three mountain ridges topped by numerous volcanic cones. While the magma cooled in these channels, it solidified into gigantic vertical basalt dykes, typical of the geological architecture of El Hierro.

The volcanic activity, principally at the convergence of the three ridges, resulted in the continual expansion of the island. A mere 50,000 years ago, as a result of seismic tremors which produced massive landslides, a giant piece of the island cracked off, crashed down into the ocean and scattered along the seabed.

This landslide of more than 300km3 gave rise to the impressive amphitheatre of the El Golfo valley and at the same time caused a tsunami that most likely rose over 100 metres high and probably reached as far as the American coast.

Although over 200 years have elapsed since the last eruption, El Hierro has the largest number of volcanoes in the Canaries with over 500 open sky cones, another 300 covered by the most recent outflows, and some 70 caves and volcanic galleries, notably the Don Justo cave whose collection of channels surpasses 6km in length.

http://www.elhierro.com/geologia-en.html

Sponge Bob · 23-07-2011 7:34pm

We are largely tsunami 'masked' by La Palma and Madeira to the north.

maquiladora · 23-07-2011 7:48pm

superscouse wrote: »

I'm sitting here in Tenerife and there is nothing about it.

This was a report from yesterday I found.

http://www.islandconnections.eu/1000003/1000043/0/33677/daily-news-article.html

There's nothing to be worried about really. It's just a very large swarm of small quakes and may indicate a new eruption may be on the way at some stage. I'd say the chances of anything more dramatic than that happening are very slim.

up for anything · 23-07-2011 7:57pm

However, if you're on holiday in the Greek Island it might pay to keep an eye on this.

http://ismosav.santorini.net/

:pac::pac::pac:

ETA: That was a joke comment. Bad joke. Sorry.

je55ie · 23-07-2011 8:08pm

up for anything wrote: »

However, if you're on holiday in the Greek Island it might pay to keep an eye on this.

http://ismosav.santorini.net/

:pac::pac::pac:

Clicked on link, cant really follow... can you explain what you see? friend heading to crete on monday!!

maquiladora · 23-07-2011 8:10pm

Edit : This updates hourly

http://www.02.ign.es/ign/head/volcaSenalesAnterioresDia.do?nombreFichero=CHIE_2011-07-23&estacion=CHIE&Anio=2011&Mes=07&Dia=23#

Iancar29 · 23-07-2011 8:21pm

I knew i seen this on tv !....

DONT WATCH IF U GET WORRIED EASILY!

https://www.youtube.com/watch?v=3jlaiJRwU6Q

morticia2 · 23-07-2011 8:53pm

Iancar29 wrote: »

I knew i seen this on tv !....

DONT WATCH IF U GET WORRIED EASILY!

That one refers to Cumbre Vieja on La Palma, though, not El Hierro.

There is also, I think, an academic dispute as to whether it would all collapse in one fell swoop (nasty wave), or in smaller sections (local, not transatlantic problems)

http://en.wikipedia.org/wiki/Cumbre_Vieja

maquiladora · 23-07-2011 8:59pm

Swarm is still ongoing.

Here's the chart from the last hour, 2 small quakes visible there.

http://www.01.ign.es/ign/head/volcaSenalesDiasAnterioresHora.do?nombreFichero=CHIE_2011-07-23_18-19&estacion=CHIE&Anio=2011&Mes=07&Dia=23&tipo=1&hora=18-19

According to David Calvo, swarm total stands at 425 at the moment.

je55ie · 23-07-2011 10:33pm

Anyone got info on Santorini??

up for anything · 23-07-2011 10:55pm

jessie37 wrote: »

Anyone got info on Santorini??

Sorry, pet, I should have put a disclaimer at the end of the post declaring that I was taking the piss because I'm a bitter, jealous, twisted person who is not going anywhere nice this summer. There has been a little bit of activity there but nothing at all to worry about. Your friend can enjoy her holiday without having to give a second thought to anything happening other than that one in 10,000 event but you'll have that anywhere.

ETA: That site won't let you in without a password. I don't have one either. I just saw a page with EQs listed for Santorini the day before yesterday so the person who posted the link obviously had a password. None of the Greek sites I've located have the names of places listed, just the co-ordinates.

je55ie · 23-07-2011 11:24pm

up for anything wrote: »

Sorry, pet, I should have put a disclaimer at the end of the post declaring that I was taking the piss because I'm a bitter, jealous, twisted person who is not going anywhere nice this summer. There has been a little bit of activity there but nothing at all to worry about. Your friend can enjoy her holiday without having to give a second thought to anything happening other than that one in 10,000 event but you'll have that anywhere.

ETA: That site won't let you in without a password. I don't have one either. I just saw a page with EQs listed for Santorini the day before yesterday so the person who posted the link obviously had a password. None of the Greek sites I've located have the names of places listed, just the co-ordinates.

Phew!.... thanks for replying, just couldn't find any info on this anywhere...and your not bitter, I enjoy your updates on here so no worries, keep up the good work...

maquiladora · 23-07-2011 11:32pm

Looks like another 7 or so (small) quakes in the last hour.

http://www.02.ign.es/ign/head/volcaSenalesDiasAnterioresHora.do?nombreFichero=CHIE_2011-07-23_21-22&estacion=CHIE&Anio=2011&Mes=07&Dia=23&tipo=1&hora=21-22

maquiladora · 24-07-2011 11:14am

Update for anyone that is interested.

The swarm continued through the night and the total number of quakes is now close to 500.

No signs of any imminet eruptions and right now the swarm has calmed down a lot.

maquiladora · 24-07-2011 5:19pm

Seems the swarm hasnt stopped, it just paused for a bit, here is the last hour.

up for anything · 24-07-2011 10:05pm

Just thinking... we should have a Kilkenny Beers or star/river watching session from the Rivercourt terrace. There seem to be enough of us around and about KK. There's the Tonynator, Maquildora (you are KK too aren't you), Min, Oscar Mike and I'm sure I've a seen a few others. We could pretend we were stuck at the top of snow covered, erupting volcano with a tornado bearing down on us.

maquiladora · 24-07-2011 10:22pm

Biggest quake of the day so far within the last hour. Can you spot it? :P

RoisinD · 24-07-2011 10:30pm

maquiladora wrote: »

Biggest quake of the day so far within the last hour. Can you spot it?

Usually I cannot decipher those charts but even I can see that one:)

Many thanks for keeping us updated, I am following this thread with great interest.

maquiladora · 24-07-2011 10:51pm

This swarm at El Hierro has now clocked up over 500 earthquakes over the past few days and its still going.

Total number of earthquakes for all of the Canary Islands last year was 88.

chucken1 · 24-07-2011 11:12pm

up for anything wrote: »

Sorry, pet, I should have put a disclaimer at the end of the post declaring that I was taking the piss because I'm a bitter, jealous, twisted person who is not going anywhere nice this summer. There has been a little bit of activity there but nothing at all to worry about. Your friend can enjoy her holiday without having to give a second thought to anything happening other than that one in 10,000 event but you'll have that anywhere.

ETA: That site won't let you in without a password. I don't have one either. I just saw a page with EQs listed for Santorini the day before yesterday so the person who posted the link obviously had a password. None of the Greek sites I've located have the names of places listed, just the co-ordinates.

So the red star isnt an eruption?? Ive friends living there

up for anything · 24-07-2011 11:40pm

chucken1 wrote: »

So the red star isnt an eruption?? Ive friends living there

According to the legend/key it looks like an 1.1 earthquake. Nothing to fret about.

If there's a mod about please could you delete my unfortunate post before the Daily Mail get here and quote my expert opinion.

maquiladora · 25-07-2011 10:21am

According to David Calvo the the total number of earthquakes in this swaem so far is now over 570.

The swarm is picking up again in the last 30 mins or so.

maquiladora · 25-07-2011 12:48pm

141_Oscar_Mike wrote: »

Where can we check out the magnitude and depth of the tremors?

http://www.ign.es/ign/layoutIn/sismoListadoTerremotos.do?zona=1&cantidad_dias=10

However it's not very useful, when I have looked at it sometimes its up to date, sometimes in hours out of date, sometimes it reverts back to the previous day and it doesn't seem to show a full list of all the quakes.

I guess they are struggling with trying to record and review all these quakes. There's been more earthquakes recorded around El Hierro in the past week than there has been in all the Canary Islands over the past 5 years combined.

Duiske · 25-07-2011 4:54pm

Maq, thought you might find these couple of blog posts by Andy Scollick interesting, if you have not seen them already. http://bigthink.com/ideas/39267

And this, a link he provided in one of the posts. Tsunami warning system for Ireland

maquiladora · 25-07-2011 5:20pm

Duiske wrote: »

Maq, thought you might find these couple of blog posts by Andy Scollick interesting, if you have not seen them already. http://bigthink.com/ideas/39267

And this, a link he provided in one of the posts. Tsunami warning system for Ireland

That blog was actually where I first heard about the swarm, always great stuff on the comments on there and some very smart people.

maquiladora · 26-07-2011 11:12am

Latest news on the earthquake swarm.

Total number of recorded earthquakes in this swarm is now over 620 with many more unaccounted for. Depth of the quakes is between 6km and 15km. But one was at 2km.
Apparently the swarm is picking up again but the internet connection from the island to some of the online charts has been offline since yesterday which kinda makes it awkward to follow.
Also this morning there has been the first indication of some ground deformation from the GPS.

Cherrycola · 26-07-2011 1:07pm

Ok, so for anyone travelling to the canaries this weekend, like say ME, should we be at all concerned?! :eek:
Should we be prepared to run to high ground if we see the any large waves, or the sea going backwards?!

Sparkles78 · 26-07-2011 1:21pm

Cherrycola wrote: »

Ok, so for anyone travelling to the canaries this weekend, like say ME, should we be at all concerned?! :eek:
Should we be prepared to run to high ground if we see the any large waves, or the sea going backwards?!

Good question, a friend of mine is heading off there too and I dont know whether to say it to her or not... dont want to worry her for no reason

Although think I woud like to know.

maquiladora · 26-07-2011 2:13pm

Cherrycola wrote: »

Ok, so for anyone travelling to the canaries this weekend, like say ME, should we be at all concerned?! :eek:
Should we be prepared to run to high ground if we see the any large waves, or the sea going backwards?!

There is no sign of anything happening that quickly. Nearly all the quakes are down below 7km, if an eruption was getting close they would be more shallow and there would be other signs too.

There might be an eruption coming in weeks/months/years but I don't think by this weekend. :P

And even if there is an eruption, that doesn't mean that there will be a landslide.

I wouldn't worry about it.

Cherrycola · 26-07-2011 2:26pm

To be honest, im not really.

Always good to know whats going on though.

maquiladora · 26-07-2011 2:49pm

There has been about 2,000 earthquakes recorded in the Canary Islands since 1986. Over 600 of those have happened in this swarm over the past few days.

Locations of all the recorded earthquakes in this swarm from July 19 to today:

snowstreams · 26-07-2011 4:21pm

Where is the caldera on this island? Has part of it collapsed into the sea?
If there was an eruption would it occur in the same area as the seismic activity?
It looks like it could occur in an inhabited part of the island, so there mustn't have been very much activity on this island for a long time?

cherryghost · 26-07-2011 4:38pm

There's 3 volcanic areas to El Hierro. The central focus is El Golfo where the bulk of the quakes are occuring, it was once a larger island before a devestating avalanche consumed half of it about 13-15,000 years ago.

Worst case scenario is more of those remains collapse into the sea but I very much doubt it will happen given the focus of the quakes in the shallow water/beach area. On top of that even if it did, it'll collapse into very shallow water and any landsliding won't be as dangerous as it could be in deeper water. It'll basically collapse into its own previous rubble.

maquiladora · 26-07-2011 4:40pm

snowstreams wrote: »

Where is the caldera on this island? Has part of it collapsed into the sea?
If there was an eruption would it occur in the same area as the seismic activity?
It looks like it could occur in an inhabited part of the island, so there mustn't have been very much activity on this island for a long time?

Hierro is a shield volcano, it doesn't have a caldera.

There have been several large collapses on the island, the biggest one is where the swarm is centered, the part where it looks like a big bite was taken out of the island!

No idea where an eruption might occur. Could be a fissure or vent eruption.

Last time it might have erupted was 1793 but there is some uncertainty if that actually happened or not. Last time it definitely erupted was around 550 B.C.

maquiladora · 26-07-2011 5:01pm

cherryghost wrote: »

Worst case scenario is more of those remains collapse into the sea but I very much doubt it will happen given the focus of the quakes in the shallow water/beach area. On top of that even if it did, it'll collapse into very shallow water and any landsliding won't be as dangerous as it could be in deeper water. It'll basically collapse into its own previous rubble.

The quakes in the swarm so far are way too small and too deep to trigger any kind of collapse. The area where the quakes are happening might be a magma chamber starting to fill but an eruption could find an easy route to the surface somewhere else away from directly above the magma chamber. The worse case scenario I think would be for the swarm to continue, getting more and more shallow until there is an explosive eruption with large earthquakes causing a collapse of some other part of the island etc.

The fact there has only been about 4 landslides there in about a million or so years means the chance of it happening is pretty small. :pac:

cherryghost · 26-07-2011 5:11pm

maquiladora wrote: »

The quakes in the swarm so far are way too small and too deep to trigger any kind of collapse. The area where the quakes are happening might be a magma chamber starting to fill but an eruption could find an easy route to the surface somewhere else away from directly above the magma chamber. The worse case scenario I think would be for the swarm to continue, getting more and more shallow until there is an explosive eruption with large earthquakes causing a collapse of some other part of the island etc.

The fact there has only been about 4 landslides there in about a million or so years means the chance of it happening is pretty small. :pac:

Well yeah that's what I meant. There's not a hope it'll happen short term at all.

maquiladora · 26-07-2011 8:37pm

The swarm is still ongoing and has picked up since this morning. Total number of recorded earthquakes in this swarm is now over 650. Latest quakes are between 6km and 17 km.

maquiladora · 26-07-2011 9:18pm

Actualidad Volcánica de Canarias are reporting more than 15 earthquakes per hour now, though nothing bigger than 2.1 and at the same depths as before so no need to worry.

lesserspottedchloe · 26-07-2011 9:59pm

I know the chances of a volcanic landslide there veeery slim but if the worst case scenario did occur-what kind of warning systems are in place and how long do ye think it would take for a tsunami to reach our shores?

maquiladora · 26-07-2011 10:23pm

laylah wrote: »

I know the chances of a volcanic landslide there veeery slim but if the worst case scenario did occur-what kind of warning systems are in place and how long do ye think it would take for a tsunami to reach our shores?

Based on this computer model of a catastrophic collapse at La Palma, about 4 hours.

http://youtu.be/ArcWdSjAkRY

There is a warning system in the planning stages.

http://www.gsi.ie/Programmes/Bedrock/Projects/Tsunami+warning+system+for+Ireland.htm

Edit : Quick update, via David Calvo...

say hello to the 700th quake in El Hierro….WOW!!!!

maquiladora · 27-07-2011 11:24am

There is no end in sight to this earthquake swarm.

Total number of recorded earthquakes in this swarm is now 768 with many more unaccounted for.

An hour from yesterday evening for example :

maquiladora · 27-07-2011 5:31pm

I've noticed that Instituto Geográfico Nacional are now only counting earthquakes in this swarm that are over 1.5 magnitude. I don't know if they are just so snowed under that they cannot review all of them and will come back to them at a later date or what but there are way more quakes on the seismogram than what is being added to the tally.

For example only 2 earthquakes were recorded during this hour but there is at least 12 on there.

Anyway, the swarm is still going strong but apart from that no other news or changes. Nobody really knows yet what (if anything) this will or won't lead to. Nothing like this has ever been recorded at El Hierro before.

Edit : Four 2.3 quakes in the last few hours, 770+ recorded quakes and still ongoing. No trend showing them getting more shallow so need to worry about an eruption anytime in the near future uless that suddenly changes.

Updated pic.

tomcosgrave · 28-07-2011 12:00am

Are there any theories being published as to what's happening? Doesn't look like an eruption is close at hand, but is it magma movement somwhere? Any idea of whether there's a magma chamber down there and if so, the structure of it?

maquiladora · 28-07-2011 9:12am

tomcosgrave wrote: »

Are there any theories being published as to what's happening? Doesn't look like an eruption is close at hand, but is it magma movement somwhere? Any idea of whether there's a magma chamber down there and if so, the structure of it?

El Hierro isn't a well studied island. The last confirmed eruption was over 2,000 years ago (there is a suspected eruption in 1793 but this isn't confirmed). They actually had to install extra GPS stations and other monitoring equipment since this swarm started because there was never a need for much monitoring there before.
It's the first time a swarm of this scale has been detected here so it's hard to know if this is something that happens every 100 years or so and never leads to an eruption or if it is something a lot more rare that only happens in the build up to something more interesting.
The swarm could be generated by magma moving but at the moment its all mostly around 10km down so nothing is going to happen imminently but it needs to be watched closely.

Earthquake Swarm (11000+) El Hierro, Canary Islands

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