El Hierro

[jand]

Data Update 27/11 – 23:50
- A total of 16 earthquakes today
 - Only 6 earthquakes were M 1.5 or greater
 - the extremely shallow El Golfo 1.9 earthquake from this morning was not followed by other shallow quakes (luckily)
 - harmonic tremor wad severe to very strong today and is still continuing that way around midnight. The IGN graph shows very strong tremor in between 20:00 and 21:00 and very strong again with a lot of powerful bursts from 22:00 on until the time of this update.

Update 27/11 – 23:30
Jesus Perez Quintero, the person in charge for Safety at El Pinar was aboard of the Salvamar when the ship navigated to the eruption spot this morning and this afternoon (see also images Joke Volta and Ian Carson). 3 heavily shaking videos were recorded during this trip. Collecting fresh lava stones was very important for science, a risky task but also well planned.  We have embedded 1 video, the 2 others have to be viewed via the link below. These videos are the same than showed in the Avcan facebook site.  The Videos are courtesy Jesus Perez Quintero and Avcan

http://www.youtube.com/watch?v=nFrHnAmwt8s

http://www.youtube.com/watch?v=AHyBiEHjQAY

[jand]

Harmonics seem to be picking up again,
.

[jand]

Avcan Copied

More than Island, the eruption is similar to the Serreta, from 98 to 2000...
http://www.volcano.si.edu/world/volcano.cfm?vnum=1802-05%3D & volpage = var

[jand]

http://adsabs.harvard.edu/abs/2009AGUFM.V51A1662L

Sometime between 134 and 21 ka, the volcanic edifice of El Hierro Island, the youngest, smallest and westernmost island of the Canary Archipelago, grew unstable and its north flank collapsed seaward to form the 15-km-wide El Golfo embayment. Since this event, eruptions at El Hierro have concentrated at the base of, and directly on, the landslide headwall and have commonly involved peculiar ankaramitic lavas rich in clinopyroxene and olivine crystals. The most striking examples of such eruptive products are located at the prominent Tanganasoga volcano, where at least ten eruptive vents have produced a large bulge in the centre-west part of the El Golfo embayment. Lava bombs from the northernmost craters reach up to ~1 m across and show extremely high crystal contents of up to 50 vol. %. Loose lapilli deposits found on the slopes of the cones contain large, often intact clinopyroxene crystals that frequently reach 1.5-2 cm, with the largest found being 3 cm across. We analyzed the whole-rock and groundmass composition of the ankaramites, as well as the composition of phenocryst phases. Moreover, four clinopyroxene megacrysts were studied in further detail, with > 300 electron microprobe spot analyses per crystal. Results indicate that groundmass and co-existing olivine and clinopyroxene crystals approach chemical equilibrium in terms of Fe-Mg exchange. Core-to-rim chemical profiles in the smaller crystals (< 1cm) reveal relatively homogeneous compositions of intra-sample crystal interiors. However, steep normal Fe-Mg zoning is common in the outermost 20-40 ìm of the crystals. In contrast, some crystals show reverse zoning towards the rim. Clinopyroxene thermobarometry indicate crystallization pressures of 700-900 MPa and temperatures of 1170-1220°C. The megacrysts show complex oscillatory zoning patterns, which, nonetheless, translate into modest chemical variations (Mg# = molar Mg/(Mg + Fetotal) = 76-80). We propose that the formation of Tanganasoga's ankaramitic magmas and clinopyroxene megacrysts is the result of a complex interplay between prolonged magma storage, regular influx of fresh magma and efficient crystal growth, fractionation and accumulation at upper mantle depth. The eruption of such dense, crystal-rich magmas probably requires forceful triggering, and appears to be facilitated after large-scale landslide events.

[fifi]

La Provincia are this morning saying that the cone of the volcano is still 200 metres underneath the water, (this is disputed by others). If it is true we will have a good while to wait before a full eruption.

The pyroclastics, which are solidified lava, in this case, by contact with water, are issued by the underwater volcano whose mouth is 200 metres below the surface, since the ship Ramon Margalef has found that the volcano, which rises 300 meters high and has 100, has not grown for weeks, even though it continues to release material. This is because, according to Alex Hansen geographer at the University of Las Palmas de Gran Canaria (ULPGC), "that a volcano grows in height, has to increase its base and the material, which is highly vesicular (porous) plus the fact that it is encased in a valley, this increase is difficult. "

The process by which these large rocks come up to the surface, instead of rushing down the slope of the cone, has to do with the fact that they are laden with  gases that make them float. Once expelled, returned to the fund.

              ...............

The lava bombs seem to be shooting quite high into the air at the moment unlike yesterday and some are travelling huge distances on the webcam. http://earthquake-report.com/2011/11/12/32535/

[jand]

Update 28/11 – 10:01
Now and then we are picking comments and bring them to a higher level. In this case we highlight the question of Mariette who had planned a vacation in La Restinga in December and booked it long before the volcano started his activity.

Question of Mariette (via our comment section)
 Thanks for your informative and interesting website and thanks to everyone contributing.
 We use to celebrate x-mas in la Restinga and have booked also for this year, long before any sign of volcanic activity showed. We shall come to Restinga 18.12, so it is some weeks to go, where many things can happen. We have the impression, however that the eruption is rather stable. But since there are so many experts following this site, I would like to hear if an explosive, destructive eruption can be expected. We shall stay 3 weeks in an apartment in la Restinga, that probably doesn't tolerate a force 4+ earthquake. What is wise to do? Thanks for any comments. Mariette

Earthquake-report.com answer :
 Dear Mariette,
 Thanks for your specific question. First of all the eruption of a volcano cannot be precisely predicted, not when exactly it will erupt and where it will erupt. We have to stress however that science has made huge steps forward the last decades. The gap to precisely predict an eruption is narrowing more and more. Very shallow volcanic quakes are a specific sign for a nearby eruption. This is repeatedly said by Pevolca, the organization guarding the safety of everybody on El Hierro. So far they have been right.
If you trust the authorities, we can advise you to make your trip. There are 2 kind of risks :
 a) volcanic risk : the vents who are currently active are approx. 1.8 km out of the coast, which is a safe distance for a normal eruption pattern. Even when a subaerial eruption would be starting, this will normally go gradually giving enough time to be evacuated if necessary. There is a team of IGN / CSIS scientists stationed in La Restinga and they are continuously (24/7) monitoring the air quality, earthquakes etc.
 b) earthquake risk : the heart of the earthquakes area is the El Golfo (north) area. The main problem there is not the shaking of the houses (every house will be more or less safe until magnitudes of 5.0, a value never reached so far), but the landslides. La Resinga has for sure NO landslide risk. This said, we can conclude that the earthquake safety risk is minimal.
 Going to La Restinga means also supporting the local economy. They really need it.
 + what in it for you ? Well, the unique experience of being close to an active volcano. This is a chance of a lifetime !
 And as a reward for my long answer, we hope that if you are at La Restinga, you will report what you experience to the thousands of earthquake-report.com readers )
 Ian Carson is not happy at all that he has to leave later tonight (his holiday is over). Believe it or not, he is making plans to return within 1 to 2 weeks.    Armand

Update 28/11 – 10:01 – Ian Carson reports
Just had long chat with scientists. Depth of vent yesterday was imprecise according to the captain. Now the real news, a new scientific ocean survey ship is coming tomorrow to map the area. It will also do work in the north (El Golfo region).

[jand]

Volcano Tanganasoga is in the centre of the line of the eartquake swarms and ridge.

[jand]

[kevin2003]

quote:Originally posted by fifi

La Provincia are this morning saying that the cone of the volcano is still 200 metres underneath the water, (this is disputed by others). If it is true we will have a good while to wait before a full eruption.

[jand]

Classification of the rocks.

[TripleH]

quote:Originally posted by kevin2003

quote:Originally posted by fifi

La Provincia are this morning saying that the cone of the volcano is still 200 metres underneath the water, (this is disputed by others). If it is true we will have a good while to wait before a full eruption.

Is that jand's pc???

[kevin2003]

quote:Originally posted by jand


Classification of the rocks.

[jand]

Avcan Translated.

The seismicity of the four last days remains concentrated in the Gulf, and Al interior of the island, in fact, several earthquakes now appear in the central area of the Gulf, both marine and land.


In addition, like previous days, turns to align according to the NNW-SSE direction, aligned from the sea of the Gulf up to the area of eruption in the sea off la Restinga, with some earthquakes in the interior of the island, one of them yesterday in the South Ridge. You can also see an alignment n-S from the Tanganasoga to the North, a couple of degrees inclined towards the East, of which there are now 3 earthquakes and other days to the South there is an earthquake in the area of the Julán and the other in the Tanganasoga. These two alignments are the most activity being the last few days.(Henry)

[jand]

Good morning, historic volcanic eruptions in the Canary Islands, 27/11/11 - in the wake of the volcanic eruption is occurring in the calm sea, South of El Hierro, the Foundation for ethnography and the development of Canarian handicrafts (FEDAC, www.fedac.org)) published in his photographic background images of historical eruptions of Canary Islands. Appear the eruption of the Chinyero in 1909, Tenerife, and the volcano San Juan (1949) and the Teneguía (1971) in La Palma., source: 'http://www.canarias7.com/multimedia/galeria.cfm?id=6976 & n = 1'

Wow have a look at the photos on the above link.

[fifi]

Love the old photos. Thanks jand.[]


There has been another earthquake over in the el Golfo area at a depth of less than a Km. There were two shallow ones there yesterday. I was reading that if these keep up that they will probably trigger an eruption over there.http://www.avcan.org/?m=Animacion

[jand]

Data Update 28/11 – 16:48 UTC
 - Medium to strong harmonic tremor
 - 18 earthquakes since midnight. The number of earthquakes has been picking up speed and strength during the first hours of the afternoon.
 - The strongest earthquake was a M 2.9 @ 13:32

[jand]

La Palma is showing movements today?

[jand]

Update 28/11 – 17:54 UTC
 Small Jacuzzi presently forming on the eruption webcam

[jand]

Avcan FB Copied Translated

I also Naomi, in fact this weekend caught my also attention earthquakes in the area of the tunnel, but as noted Henry, will have to be alert to see what happens in the coming days, if they become repeated and more frequent because then it will be a sign of something more. That is not to say that the tunnel would have to remain open, otherwise, one can never tell when a stronger quake, that nobody knows when it may be, to produce a tragedy that could have been avoided.
See Translation

[fifi]

Eruption filmed under the sea.http://www.youtube.com/watch?v=hmMlspNoZMs&feature=player_embedded

[Paddster]

[kevin2003]

[SurfJames]

Good Evening fellow Volcanists.

Just come home after a shift in the hospital and a BIG THANK YOU to jand and fifi (and any one else who has contributed) for your posts.

It's great simply tuning in and being fully informed with respect to todays events.

And...Wow....Earth quakes seem to be getting shallower at times, and as we know, these quakes are due to magma making it's way up towards the surface.

I find it amazing that when two plates slide; one under the other, the pressure is so great that the friction causes the rock to melt at their contact points!

[fifi]

Hi Surfjames, well still waiting for my Roosters....im a patient woman.[]

[kevin2003]

quote:Originally posted by fifi

...im a patient woman.[]

[SurfJames]

quote:Originally posted by fifi

Hi Surfjames, well still waiting for my Roosters....im a patient woman.[]

I've always been very attracted to patient people [][][][8D]

But - YES - we want roosters!!!!

[jand]

Morning Everyone

Data Update 28/11 – 23:24 UTC
 - Strong to very strong harmonic tremor with occasional massive bursts
 - 4 earthquakes since midnight UTC
 - strongest earthquake 3.0 magnitude
 - depth from 15.1 until 20.3 km
 - air quality at La Restinga : very good
 - weather outlook : : beautiful sunny weather today, wind blowing from the east, maximum wave height : 0.8 meter, max. wind speed : 3 knots

--------------------------------------------------------------------------------

Data Update 28/11 – 23:24 UTC
 - Variable medium to strong harmonic tremor
 - 20 earthquakes today
 - strongest earthquake 2.9 magnitude
 - depth from 14.7 until 22.6 km
 - air quality at La Restinga : very good

Pictures of the day from Joke and Ian
 Not too much activity today. Ian did spend his last day at El Hierro walking around the beautiful landscape and enjoying for the last time the great views on the colorful Las Calmas sea.
Ian Carson wrote : What do you do when the Volcano goes quiet, become a tourist again ! Walked about the Restinga area keeping an eye on the sea and climbing all the cones. I went up the Restinga Cone at the back of the town. An image shows the webcam mast and the village of La Restinga. The other webcam is also up there, solar powered with a transmitter. The beauty of el Hierro still continues to unfold. The stain was vivid and ever present today. The 'fake Jacuzzi', near to the coast and Port must have appeared on the webcam. I photographed this feature this morning to show it – thinking it may be confusing. Pleasant last day, easier to leave when activity is low...  Click on the images to see the whole set of today's pictures.

https://picasaweb.google.com/110327184570944806725/ElHierroNovember282011?authuser=0&feat=directlink#

[jand]

http://212.170.244.196/

Unless its my eyes think there are bubbles again?

[fifi]

Morning jand, yes it looks like it to me too in two areas.

[fifi]

quote:Originally posted by SurfJames


I've always been very attracted to patient people [][][][8D]

But - YES - we want roosters!!!!

          ..........

Im very nosey.[] Are you a nurse Surfjames?