Earthquake Swarm (11000+) El Hierro, Canary Islands

eskimocat

WOW the amount of action there is incredible! Just thinking about what it would be like if something like that was happening in Ireland, specifically Leitrim and I knew that there was over 900 earthquakes happening underfoot! :eek:

lol on the bright side, it puts a whole new slant on that old chestnut " did the earth move for you darling! " , you'd be kinna hoping that it didn't!

dlofnep

Random fact about El Hierro - It's to become the first island that generates it's power completely through self-sufficient means (solar/wind/sea).

up for anything

From http://bigthink.com/ideas/39271

LURKING on July 30, 2011, 2:32 AM
A few days ago, I posts a SWAG plot ($%#$ wild arsed guess) about how long it would be before anything manifested itself at the surface of El Hierro.

I have updated that plot with newer quakes, and so far my reverse prediction has held true… but the quakes have gotten much more vertically spread out than they were.

El Hierro is still jumping… but I don’t know what it is. In the profile plots they are starting to accumulate in a cluster centered at about 10.9 km deep. It might actually be a magma chamber.

First, the depth vs time.

http://i53.tinypic.com/scddae.png

Now the view North (note, color denotes magnitude)

http://i54.tinypic.com/348pw0l.png

View East

http://i53.tinypic.com/v2z5f7.png

Sorry I haven’t gotten to this sooner, it’s been a long week troubleshooting antiquated biometric devices, literally… in the middle of nowhere.

Pa ElGrande

Source

Q: Why do so many earthquakes occur at a depth of 10km?

A: 10 km is a "fixed depth". Sometimes data are too poor to compute a reliable depth for an earthquake. In such a case, the depth is assigned to be 10 km. In many areas around the world, reliable depths tend to average 10 km or close to it. For example, if we made a histogram of the reliable depths in such an area, we'd expect to see a peak around 10 km. Thus, if we don't know the depth, 10 km is a reasonable guess. We used to use 33 km. Increased understanding indicates that 10 km is more likely. Some areas, like subduction zones, are known to have many earthquakes much deeper than 10 km. In those areas, probably a larger fixed depth would be appropriate. The most common reason for having to fix the depth is that the earthquake occurred too far from the nearest seismic station. A useful rule of thumb is that a reliable depth requires that the distance from the epicenter to the nearest station must be less than the depth of the earthquake. Modern computational and theoretical advances can now produce reliable depths at greater distances from the nearest station, so the rule of thumb does not always apply nowadays. However, the rule of thumb does illustrate one conclusion: fixed depths are more common for shallow earthquakes than for deep ones.

maquiladora

Seismic activity has dropped a lot now. Just a couple of small quakes this morning, a big change from recent days.

It could be that this is winding up now and nothing will come of it or it could be just the end of one phase, no way of knowing.

The latest GPS data shows no significant ground displacement so an eruption is still not looking likely anytime soon.

Edit : Updated earthquake figure is now 997.

up for anything

From BT: http://bigthink.com/ideas/39524

LURKING on July 30, 2011, 5:16 PM
Brought forward from the previous gnome infested thread, repaired and reposted.

@Bruce Stout on July 30, 2011, 3:38 AM

“…Could you also perhaps plot frequency of quakes over time? That would be great. A rough squizz at your first chart seems to show a bit of a pattern.”

Yeah… I saw a pattern too. But I don’t think it’s the same one. This pattern has me puzzled.

But first, the quake count over time. I used “number of quakes per hour” as the criteria.

http://i53.tinypic.com/2d6ejs.png

And, while plotting the quakes from a plan view. I saw a hole.

Yep.. literally a hole in the quake pattern.The hole is about 728 meters across.From the previous profile plots we know that the centroid for the cluster is about 10.9 km down. But why is there a hole slap dab in the middle of it. This is gonna take the explanation of a bona-fide geologist to explain because I don’t have a clue. Here’s the hole. http://i55.tinypic.com/2r3eg3t.png

LURKING on July 30, 2011, 5:55 PM

I exported the quakes to a Google KMZ in order to see what might be in the area of “the hole”

Here is the view from Goog Earth:

http://i53.tinypic.com/2dqve3o.png

And a view looking to the east.

http://i52.tinypic.com/2mebfhi.png

Apparently, this “hole” (less quake density than the surrounding cluster) is right next to a previous focus of past activity.. that is if I’m looking at it correctly.

This “hole” is apparent all the way down through the cluster… which is centered at about 10.9 km deep.

je55ie

Thanks up for anything!

Can you explain what a hole would mean, or does anyone know?

blacktalons

July 30, 2011 – CANARY ISLANDS – Recently El Hierro volcano of the Canary Islands has been experiencing a seismic swarm beneath it, which as of yesterday reached to over 700 events. Most of these events have been at Magnitudes of around 2 (+/-0.5) and are clustered beneath El Hierro whilst the depths of these earthquakes have been roughly between 9 and 16 km for the most part, with the exception of a few shallower and deeper quakes, the shallowest of which has been around 4 km (as of 27/04/11 8am GMT for the plotted data below) but as shallow as 1 km following this. If we look at these earthquakes in two plots here we can see the clustering of these earthquakes is mainly confined to an oval area at 10 km depth. El Hierro is a broadly basaltic volcano which might have been active in 1793 although this is uncertain. –Earthquake Report

up for anything

It's not an actual hole but a hole in the quake pattern. I don't know if anyone else has spotted this 'hole' but this is Lurking's guess at what it might be.

LURKING on July 30, 2011, 5:34 PM
Maybe the “hole” marks the boundaries of the bottom of the hardened “plug” from a previous eruption?

LURKING on July 30, 2011, 6:38 PM

MOST LIKELY, what I have found is an artifact of previous activity there and represents an area of rock that is much tougher than the surrounding material. It is probably a previous magma pathway with a hardened section of material in it. The quakes indicate fractures in the rock around it, but the forces aren’t strong enough to break it.

No… I don’t know what that means in the long term. I’m not even going to hazard a guess.

El Hierro Airport.

ANITA ... on July 30, 2011, 7:23 PM
Being a small island the airport of El Hierro was only open 12 hours everyday.

Two days ago things changed and now it can operate 24 hours for day in case of emergencies and I quote the minister Narvay Quintero:

“la apertura del aeropuerto durante las 24 horas para casos de emergencia pone fin a una situación inaudita dado que, hasta ahora, la isla estaba incomunicada 12 horas diarias por vía aérea, planteándose un grave perjuicio para los múltiples traslados sanitarios y en la intervención de medios aéreos en casos de catástrofes naturales como incendios”.

Translation:
“The opening of the airport for 24 hours in cases of emergency puts an end to a situation where the island had no areal communications for 12 hours, that was bad in cases like emergency medical transport and natural disasters, like forest fires”.

(sorry if the translation is not perfect)

link: http://www.eldia.es/2011-07-29/islas/islas0.htm

and

http://www.eldia.es/2011-07-28/ISLAS/13-aeropuerto-Hierro-podra-operar-horas-casos-emergencia.htm

Coincident or not?
Only time will tell…

maquiladora

The swarm did pick up a bit again yesterday, there were some more quakes but mostly small. It is still ongoing at the rate of a couple every hour or so at the moment.

Recorded earthquake total stands at 1,014.

maquiladora

Recorded earthquakes for yesterday have been updated. The swarm is still ongoing and picked up slightly in the past couple of hours.

Total now : 1,042

Interesting north/south pattern under the island with yesterdays & todays quakes :



Still no significant ground deformation or any changes that indicate anything will happen on the surface any time soon.

maquiladora

Swarm has picked up again, some slightly bigger quakes being recorded now.

This is the last hour :



And these are today's earthquakes so far, almost all in that north/south line under the west side of the island. One was a 2.1 at 5km, almost all others still around 10-13km mark.

thetonynator

Whats the biggest quake recorded in this swarm so far do you know?

maquiladora

thetonynator wrote: »

Whats the biggest quake recorded in this swarm so far do you know?

I think it was a 2.7, not very big.

The swarm has slowed/paused again now, hasn't been an earthquake recorded for 3+ hours. It seems to go in phases or pulses.

Total accounted for : 1,070+

maquiladora

Not sure exactly whats happening on El Hierro today. Trying to translate from Spanish is tricky sometimes but it seems that IGN (the Spanish authority monitoring the earthquakes) has reduced the resolution of the sensor on the island. I'm not sure if this is the reason why little or no earthquakes have been recorded all day.

Anyway, here is an image of the plumbing system of El Hierro:

http://twitpic.com/5z9agg

up for anything

Erik Klemetti has a new blog post up over on Big Think concerning El Hierro.

EARTHQUAKES UNDER EL HIERRO IN THE CANARY ISLANDS: WHAT CAN WE EXPECT?

maquiladora

up for anything wrote: »

Erik Klemetti has a new blog post up over on Big Think concerning El Hierro.

EARTHQUAKES UNDER EL HIERRO IN THE CANARY ISLANDS: WHAT CAN WE EXPECT?

Very good synopsis.

No new earthquakes getting reported, so as far as I can tell, the swarm seems to be coming to an end, at least for now.

I'll keep an eye on it but there's no need for updates now unless its kicks back off again.

maquiladora

After a couple of days of virtually nothing, in the last hour there has been a sudden rash of small earthquakes.

Looks like around 50 here in the last hour....

maquiladora

There hasn't been any let up in this new phase of the swarm since I posted last night.

No idea on the total figures yet, some have been recorded but it's going to take a while for IGN to sort through them all and add them manually.

It seems they are all down around the same depth as the earlier phase of the swarm and they are all mostly small or very small earthquakes.

Here is the last hour. Each 'squiggle' you see is an earthquake, each line represents 3 minutes of time.

maquiladora

Now this is just getting silly... :pac:




No sign of this very intense phase ending. IGN are only adding 1.5+ earthquakes at the moment, they will have to add all the many, many smaller ones whenever they can get a chance.

There has been about 400 to 500 earthquakes since last night.

Hmmmmmm.......

up for anything

Maybe it's just God adjusting his floorboards in lieu of moving his furniture or one of those conspiracy theory stargates. I wonder what's going to happen, if anything. It seems like a lot of sudden movements just to trickle away to nothing but it's happened before in other places.

maquiladora

up for anything wrote: »

Maybe it's just God adjusting his floorboards in lieu of moving his furniture or one of those conspiracy theory stargates. I wonder what's going to happen, if anything. It seems like a lot of sudden movements just to trickle away to nothing but it's happened before in other places.

Yes the chances are this will lead to nothing. But nothing like this has ever been recorded here before so there is a lot of guessing going on. We are just assuming that this is normal and we just werent around to detect it when it happened in the past. The alternative is that this is something more rare that precedes something more interesting.

Looking at the above graph, the current phase of the swarm looks a bit more vertical. Hopefully Lurking and the other plotting experts of the Eruptions blog will make some sense of it.

up for anything

Macqui, I don't know if you've come across this link. Might be of some interest to you. Ignore otherwise.

http://www.avcan.org/?m=Noticias&a=noticia&N=890

I think I've seen this one posted before but just in case.

http://www.meteolaspuntas.es/

A nice eruption on an easily evacuated island would be topping just now. I'd get in some of Aunt Fanny's high teas and lashings of ginger beer for the weekend if it seemed likely. Knowing what I know now, I suspect Uncle Quentin worked for HARRP or at the very least was developing a new strain of Ebola for some bad man.

Hekla has had a couple of very interesting quakes according to those in the know especially as she is known aseismic until an eruption occurs.

maquiladora

up for anything wrote: »

Macqui, I don't know if you've come across this link. Might be of some interest to you. Ignore otherwise.

http://www.avcan.org/?m=Noticias&a=noticia&N=890

I think I've seen this one posted before but just in case.

http://www.meteolaspuntas.es/

Yeah AVCAN do a great job of turning the IGN data into handy graphs and charts.

Btw, here is the last hour...
http://www.01.ign.es/ign/resources/volcanologia/CHIE/imagenes_sismica/HORA/CHIE_2011-08-04_18-19.jpg

fizzycyst

What could the fact that they stopped for a couple of days mean I wonder? I read in one of the articles that you or someone else posted that these quakes happen all the time beneath the surface in Iceland and Hawaii, but starting and stopping like that has to be strange.

up for anything

http://bigthink.com/ideas/39589

BORIS BEHNCKE on August 4, 2011, 3:36 PM

El Hierro to me looks a lot like a volcano heading toward eruption – I would not expect anything apocalyptic there, rather a typical basaltic scoria-cone-forming eruption, Hawaiian- to Strombolian-style. Nothing to force some of you poor people to flee up the hills as far away as somewhere in the north of the British Isles …

thetonynator

Sooner or later, the dots on the map showing the locations of the earthquakes will spell out a secret message . . .:pac:

up for anything

thetonynator wrote: »

Sooner or later, the dots on the map showing the locations of the earthquakes will spell out a secret message . . .:pac:

And it will say, the tidal wave will reach as far as and just past South Kilkenny. All those in the city will be saved while the Sodom and Gormorrahs of Piltown, Mooncoin and Fiddown will rest with Atlantis beneath the ocean waves.

maquiladora

up for anything wrote: »

And it will say, the tidal wave will reach as far as and just past South Kilkenny. All those in the city will be saved while the Sodom and Gormorrahs of Piltown, Mooncoin and Fiddown will rest with Atlantis beneath the ocean waves.

Have you been smoking some dried National Geographic documentaries or something?

up for anything

maquiladora wrote: »

Have you been smoking some dried National Geographic documentaries or something?

My secret is out!