El Hierro

[jand]

Thanks SurfJames x

[jand]

Update  06/12 – 18:48 UTC
 IThe new depth of the vent and results of the research vessels missions will be published and explained tomorrow after the Pevolca meeting of 1 PM UTC.

[jand]

volcanocafe copied.

Seismostratigraphy of the western flanks of El Hierro and La Palma (Canary Islands): a record of Canary Islands volcanism" by Urgeles, Canals, Baraza, and Alonso

can be found here:

http://geomar.geo.ub.es/eurodom/documents/Urgelesetal98_MG.pdf

[jand]

Update  06/12 – 21:14UTC
 Joke reports a Rotten Egg smell in La Restinga. Locals are saying that this happens regularly after sunset when the landmass is cooling and the wind inverses from the sea to the land, carrying the H2S to the coast

[Florence]

quote:Originally posted by jand

TripleH

I am not a scientist or a specialist on Volcanoes I can only read the information and comments as anyone else can from the information graphs maps and comments I post which are from other sites organisations and people.

IMO I still think that Tansganosa has something to do with all this (but of course I may be wrong) and I think whatever is happening is still underway and has not stopped.

Sorry?  What is Tansganosa?  Searches on Google have not revealed anything.

[SurfJames]

quote:Originally posted by Florence

quote:Originally posted by jand

TripleH

I am not a scientist or a specialist on Volcanoes I can only read the information and comments as anyone else can from the information graphs maps and comments I post which are from other sites organisations and people.

IMO I still think that Tansganosa has something to do with all this (but of course I may be wrong) and I think whatever is happening is still underway and has not stopped.

Sorry?  What is Tansganosa?  Searches on Google have not revealed anything.

Hi Flo,

Tanganasoga is the mainland volcano, directly in line with / in the middle of / the earthquakes. One theory is that magma is rising up through existing lava tubes and rifts and then it will erupt.

But, I think you possibly already knew that []



[][8D]

[jand]

Update  06/12 – 23:44UTC
 - The rotten egg odor has also been confirmed by AVCAN followers. See the H2S values measured tonight in real time at the La Restinga analysis container station.

The coincidence of the high H2S levels with the very strong harmonic tremor has to be looked at. A pity we could not see the Las Calmas sea at night. The high values may have been triggered by a very strong Jacuzzi activity.




 - The picture below shows a very long lasting burst of activity that started at 21:26 UTC and lasted for about 20 minutes. The signal decreased gradually thereafter but stayed stronger than before the burst
 - 2 earthquakes today with epicenter in the El Golfo Bay.

[waggy]

quote:Originally posted by jand

Update  06/12 – 21:14UTC
 Joke reports a Rotten Egg smell in La Restinga. Locals are saying that this happens regularly after sunset when the landmass is cooling and the wind inverses from the sea to the land, carrying the H2S to the coast

Google anabatic and catabatic winds, Jand.

[jand]

The red light by eruption will be limited to the maritime zone on the volcano

Valverde (El Hierro), 7 Dec (EFE).-the leadership of the Special Plan of Civil protection by volcanic risk (Pevolca) has been agreed today limit the red light by eruption to the sea on which stands the submarine volcano of El Hierro, in addition to enable a maritime route for the transit of ships at La Restinga.

Until now the red light affected around the fishing village of La Restinga and since the decision taken today by the Pevolca this town, like the rest of the territory of El Hierro, it will be to hold the color "yellow" indicator of risk volcanic, as announced at press conference the director-general of security and the Government's emergency CanaryJuan Manuel Santana.

The director-general has pointed out that this indicator continues operating in yellow because remains the underwater of magma emission situation, although "an approach to land" has not been detected and in any case, in the depths that registers the eruptive process it not affect the population.

Also, with the aim of facilitating the transit of ships by the port of La Restinga is enabled a strip of navigation of 0.25 miles glued to the coast and four miles to the area of maritime exclusion on the submarine volcano.

María José Blanco, scientific spokesman of the Pevolca, has pointed out that the eruptive process in the South of El Hierro "continuing" and pointed out that they have appeared on the surface of the sea smoldering lava fragments in a manner "intermittent, but continued".

However, scientific spokesman stated that they have decreased the frequency and magnitude of earthquakes, since last week have only located 28 movements at a depth of between 15 and 25 kilometers and only one had a magnitude greater than 3 on the Richter scale.

The quality of air, white has been added according to the parameters studied values are normal, but yesterday the inhabitants of La Restinga reported that from the 20: 30 hours felt headache and perceived bad odor.

This is why scientists are going to study what component of the air can be producing these "sensations" and this sampled and placed new instrumentation to measure continuous quality of the air in this area of the costa herreña.

As to bathymetry held on December 4 by vessels "Ramon Margalef," of the Spanish Institute of Oceanography, and "Sarmiento de Gamboa", of the Consejo Superior de Investigaciones Científicas, indicates that the issuing of magma Center is located at a depth of between 160 and 180 meters.

María José Blanco has stressed that this data indicates that the issuing Center remains "in the same position" but had also stressed that the information is still "very preliminary" and will be divulged later in the "more elaborate" form.

[pennylane]

Like most fams, December is manic in this house so not much time to get on the PC but I keep popping in for an update, thanks guys xx
Glen x

[jand]

volcanocafe Copied.

mirri says:

 December 7, 2011 at 18:58

At AVCAN and other forums people are discussing these decisions, and many (including me) think its too soon to put down the alertlevel and let boats enter the harbour etc. Some also mentioned the 2009 earthquake in L'Aquila, Italy, where 308 people died and the scientific committee is charged for failing to give people adequate warning:

"Do Bad Earthquake Predictions Kill People? No. But Bad Risk Communication Might"
 http://bigthink.com/ideas/40382?page=all

A good quote from this page:
 "Fear is good. It helps protect us. But getting risk wrong — worrying more than the evidence says we need to, or not as much as the evidence says we should — produces stress and leads to unhealthy choices for ourselves and for society."

Lets hope its something similar IGN and Pevolca had in mind, that people should be worried but not too worried.

Btw, tremorsignal is picking up a bit again, I think Bob wants to join the discussion...
http://www.ign.es/ign/resources/volcanologia/CHIE/imagenes_sismica/DIA_SP/CHIE_2011-12-07_sp.jpg

[jand]

earthquake-report.com

Update  07/12 – 17:21 UTC
 - Harmonic tremor is continuing to be medium to strong.

Update  07/12 – 16:21 UTC
 - As one could understand, opinions at El Hierro are very mixed (to say the least). Some people are arguing that the decision is "politically motivated" as the decision has been taken only 2 days after some action groups were calling for an immediate lifting of the alerts.  Coincidence ? For some people yes and others NO.
 - Many people cannot understand the red alert maritime zone.  They say, we don't swim that far in the sea . Others are telling that 150 meter is not that deep at all and that the volcano is sending almost continuously lava to the surface since a couple of days. Pevolca has declared that they have decided to lift the alert because they are currently excluding a land based eruption.
 - there seem to be two different depth data sets available a) Sarmiento da Gamboa 150 meter and b) Margalef 160 to 180 meter.

[duncolm]

quote:Originally posted by jand

volcanacafe copied.

suzie says:

 December 6, 2011 at 11:13

UK Met Office preparing for a Hekla eruption??

http://www.metoffice.gov.uk/aviation/vaac/vaacuk_vag.html

The London Volcanic Ash Advisory Centre is one of a worldwide network monitoring ash clouds and issuing warnings, particularly for the aviation industry. The map at http://www.metoffice.gov.uk/aviation/vaac shows the area of responsibility for the various centres worldwide. The London patch includes the North east Atlantic, and they are responsible for issuing reports in respect of any Icelandic eruptions.

Looks like they have been running an exercise in November based on Hecla. In September the exercise was based on the Norwegian volcano Jan Mayen.

They use observations from the ground and from pilots, together with satellite images to monitor the presence of ash clouds, and add information from weather forecasts to predict the movement of the ash. Since the Eyjafjallajökull eruption they are expected to give more detail on the density of ash clouds, so I'm not surprised that they're running tests.

[jand]

http://www.ign.es/ign/head/volcaSenalesAnterioresDia.do?nombreFichero=CHIE_2011-12-08&estacion=CHIE&Anio=2011&Mes=12&Dia=08

Intersting graph from midnight today.

[jand]

earthquake-report.com

Update  08/12 – 08:28 UTC
 - We wrote the 07:18 update when it was still dark
 - Reader Max wrote in our comments at 07:33 : Well, regardless of tremor changes, smoking lava stones are still coming up to the surface at 7:30 camera time. It's still ongoing.
 - and .... indeed tremor is gradually picking up again = the eruption continues

[jand]

Update  08/12 – 11:34 UTC
 - Smoking lava stones can be seen now and then, which proves that the vent is still active.
 - We are happy that the best webcam (RTVC) works again.
 - Julio del Castillo Vivero was able to (screen)capture a strong smoking lava block at 11.11.37  this morning.

[jand]

Volcanocafe Copied.

GeoLurking says:

 December 8, 2011 at 16:58

Sort of what I have stated. There may be something to the quakes dropping in elevation and increasing in magnitude as they made their transit south, and the eerily quiet region from the swarm to the actual jacuzzi... no quakes.

The latest "wad" has been located in what is ostensibly the upper mantle, possibly a recharge of the overlying area emptied out by Bob... the lower periphery of which seems to correlate with the upper "wad" of quakes across another... eerily quiet area. The upper group is withing the 68% one SD boundary from the original swarms average depth. (points to them being in the same "family")

Early on, back when this all started... this showed up.

http://i42.tinypic.com/1t66gl.png

Its a hole. Slap dab in the middle of the swarm. At the time I attributed it to "tougher" material, I wouldn't go as far as to call it a "plug." It's pretty much under the dominant cone along the E-W ridge line.

[jand]

http://www.youtube.com/watch?v=PHloWaSDtng&feature=player_embedded

el hierro EQs by depth.wmv

[fifi]

Hi jand, do you understand what GeoLurking is saying in his post? Im a bit lost.[]

[TripleH]

Reading it Lady Fifi, I would shay he ish pished

[jand]

Earthquake between Gran Canaria and Tenerife:
1116605 08/12/2011 19: 51: 27 28.1080 - 16.1280 2.2 4 ATLÁNTICO-CANARIAS without depth indicated by IGN. In this image the olicy are the earthquake today others are old that indicates Google Earth.
(Humberto)

[jand]

Fifi these were the posts before


GeoLurking says:

 December 8, 2011 at 15:47


Edward Lane says:
 December 8, 2011 at 11:00

"@Lurking – question (above) for you regarding your 23.09 and 23.59 pngs yesterday evening – azimuth and depth – basically it looks like there are a few correlations, but perhaps I'm just seeing patterns being human."

Sometimes when you see patterns, they are real.

In this case, those plots are not generated to look for specific correlations. They are intended to offer a view at some characteristics about the rock and quakes that we don't usually see... the overall orientation trend of the fracturing.

Thats' why I didn't get bent out of shape about no one quake standing out. I don't want to see one individual quake, I want to see groups of quakes.

A few posts ago.. possibly weeks or more, I mentioned that earthquakes only occur when the stress on the rock (or strain) accumulates faster than the rock can get out of the way or accommodate that force by deforming/bending. Even window glass, that hard brittle stuff that is known for shattering, will ooze and deform... given enough time. (go look at the original windows for multi hundred year old buildings) And glass... is predominantly silica. SiO2. Yep. That same substances that distinguishes a riolita from a traquita. (Rhyolite from a Trachyte)

In the case of my plots, you are looking at (possibly) overall fault planes. The direction that the material tends to crack. It is possible that you are seeing an artifact of how this area of the crust initially formed back when it accreted from the spreading ridge that became the Atlantic ocean, with the "grain" of the crust paralleling that. Yet another possibility is that you are seeing the trend of the quakes paralleling previous dike emplacements from thousands of years ago.

What I find interesting is that the trends in the orientation sort of agree with the alignment axis of the quake swarms. That may support the second case, or the whole she-bang could be related to the first case. (the original accretion along the MAR)

As for "correlations," that batch of shallow quakes you noted are related to Bob... sort of. They are actually south of Bob, and do sort of point to an overall expansion of the ridge as it is widened from north-south. (cracks trending east-west). That particular batch of shallow quakes happened after the tremor started (within about a day or so).

My interpretation is that when the quakes deviate from the trend of their siblings in orientation, it is because something much more energetic is going on than slow stresses that just barely exceed the materials ability to accommodate it. Not only would you get larger quakes, you would get more haphazard fault orientations.

Dunno if it confuses or helps.

Reply


Edward Lane says:

 December 8, 2011 at 17:50


Ah well that makes sense to me anyway (I did 'A' lvl Geology back in the day – and your interpretation at the end sounds interesting – we should probably keep an eye out for clumps of unusual azimuth quakes and see if they continue to support that idea (or not)

Reply


Peter Cobbold says:

 December 8, 2011 at 21:30


"..something more energetic going on..."
 I can go with that.
 Carl has a post from me in his inbox tthat's relevant.
 Nudge, nudge.

Reply


Betty says:

 December 8, 2011 at 21:45

There is a paper regarding predicting eruptions by mapping the changes in orientations of "double-couple fault-plane solutions" by Romana, Neuberga, and Luckettb. Also, another paper by Romana, et al. regarding that and S-wave splitting in regional earthquakes as a way to predict eruptions. What is shear-wave splitting?

[jand]

mirri says:

 December 8, 2011 at 21:53


A few days ago there were some comments about earthquakes around the other Canary Islands, and I mentioned the Volcán de Enmedio between Gran Canaria and Tenerife which for many years have had 1-3 EQs a week. At 19.51 today there was a 2,2 EQ in that area again, and at this photo todays EQ is marked with waves (the other dots are earlier EQs):
 http://a5.sphotos.ak.fbcdn.net/hphotos-ak-ash4/s720x720/384329_10150458406538447_163883668446_8592292_14646477_n.jpg

While reading about the volcano now, I found this interesting photo that I wanted to share with you. It shows every EQ on the Canary Islands between 1989 and 2009 – an average of 127 earthquakes a year (before Bob...)
 http://fotos01.laprovincia.es/fotos/noticias/646×260/2011-08-23_IMG_2011-08-23_12:06:31_sismicidad.jpg

Reply


Peter Cobbold says:

 December 8, 2011 at 22:04


Yes at 127 per year the Canaries are hardly a seismic hot spot. Which is why I am intrigued as to why Prof Sagiya built a comprehensive GPS network there – what did he know? did he expect something like Hierro's swarms?

Reply

[jand]

This is interesting this is a map of all the eartquakes in the Canary Islands from 1989 - 2009 on average only 127 per year.

Look there are none showing on the ridge on El Hierro.

[jand]

Volcancafe Copied.

Morning all, Lurking's EQ silent zone?

Latest IGN all EQs localization: "hole" in the EQs marked in red, projected into the depth plots. Obviously the silent zone doesn,t go straight down (as possibly shown in my depth schcan) but, the projection drops through a very quiet zone at the top the lat/ depth plot and another quiet zone below -15km. Also there's a quiet zone below -22km on the lon/ depth plot.

I hope this is not stating the utterly obvious, helps me understand anyway...

[fifi]

Thanks jand.[]

[jand]

Fifi/SurfJames/Glen or anybody does the above statement I hope it does not mean the obvious relate to Tansganosa (apologies if spelt wrong).

Is the red hole on the ridge .

I dont really understand what he is trying to say.

[fifi]

I think I understand it a little bit. The quiet zone is the area in Tanganasoga where the main volcano is approximately and its missing out on some of the earthquakes because the structure is stronger. Is that right or am I still lost? Its quite confusing but he seems to be figuring out where the land will be the weakest.

Is he trying to figure out what depth there might be a plug in the volcano maybe if the quiet zone is only there at certain depths? I will have to look at it again and try and analyze what he is trying to say. When you look at the Avcan youtube video that you posted yesterday you can see that the e hole is only there at certain depths.

From an earlier post....

"Its a hole. Slap dab in the middle of the swarm. At the time I attributed it to "tougher" material, I wouldn't go as far as to call it a "plug." It's pretty much under the dominant cone along the E-W ridge line."

[jand]

Volcanacafe Copied.

See Lurking's comment and sub comments up the page (8th dec 1658) for a bit more discussion on this.

The red circle (may not be obvious) on the map I just posted shows an area where no EQs have occured. So we know that that represents a "hole" going all the way down where no EQs have occured: "silent area." Silent areas surrounded by EQs may; I repeat, may be areas which contain magma or may be made up of more dense material, (Lurking's 1st thought was a plug). If you follow the projections down (red rectangles) you can see that our original "hole" meets/ joins other "silent areas" deeper down, larger areas. Can also possibly be seen on my depth schcan video posted above.

Hope this helps

[jand]

Thanks Fifi looks like you are spot on as the other comment I have just posted relates also to a dense area so really the magma is still moving but hitting a blockage hence no earthquakes.

The vent is still active so I suppose we again are in the lap of the gods!!!