General Volcanic Activity Thread!

[GulberwickWeather]

I just wonder if at that point something gave way, and magma is now on the move again, the tremor is gradually winding up again.

[Martin M]

Just read something on twitter saying journalists are ordered to attend an urgent press conference at 19.00 http://twitter.com/#!/jesusagomar/status/124155543249104896

[heroweeny]

The island media have been called to an emergency conference in the capital by the authorities for 7pm.

[GulberwickWeather]

I suspect an evacuation of the entire island may be on the cards......

[GulberwickWeather]

The webicorder seems to have packed in. There was a chunk of missing data and now it seems to be flatlining

http://www.ign.es/ig...1&Mes=10&Dia=12

No, its me lol, there it goes again

http://www.ign.es/ign/head/volcaSenalesAnterioresDia.do?nombreFichero=CHIE_2011-10-12&ver=s&estacion=CHIE&Anio=2011&Mes=10&Dia=12&tipo=1

Edited October 12, 2011 by GWW

[Martin M]

Tremor seems to be gathering strength again now, and it seems there might be some webcams getting installed soon according to someone on eruptions blog.

[The PIT]

I see Jon Frimann isn't impressed with the lack of info in English. Scientist aren't very impressed either due to lack of equipment and would love a boat out there so they can get a better idea of what's going on.

[Martin M]

I see Jon Frimann isn't impressed with the lack of info in English. Scientist aren't very impressed either due to lack of equipment and would love a boat out there so they can get a better idea of what's going on.

Yes it seems a little chaotic over there, what with the different authorities seemingly taking it in turns to release news and the lack of equipment. Its not like this has happened 'out of the blue' as the earthquake swarming on the island has been going on for some time now, surely enough time to get some form of proper action plan into place, stating who will release information ect.

[Crepuscular Ray]

Why can't John Frimann use an online translation program like anyone else? Given how this might pan out, the priority of the local authorities is doubtless ensuring the safety of the population not catering to bloggers or news agencies.

As far as I'm aware, they did put some extra equipment in, but presumably no Spanish government agency has got funds to throw about at the moment.

The last place any sane person would want to be is on a boat off the island at the moment, surely (well less than about 15km anyway)? Degassification would sink any boat and given that the wind's from the north, the risk of being sunk from below is outweighed only by the risk of being bombarded from above.

[tinybill]

this the latest i can find

Current Volcanic Islands (AVCAN)

Impressive tremor, we know from where it broke, it seems the news conference PEVOLCA confirmed eruptive process in place at two different points by the presence of two spots in the sea, with a strong sulfur smell and appearance of dead fish. The distance of the ongoing eruption of the Restinga area 1 - eruptive mouth: 5.5 - 7 miles - 970-1000 m deep ... See more

d

2 - eruptive mouth: 2 - 2.5 miles - 700 m depth

3 - eruptive mouth: 1 - 1.5 miles - 500 m deep The question is, will continue to approach the island?. In the 1 have left images, I guess in the news in a few minutes more will not lose them ... (Enrique).

Edited October 12, 2011 by tinybill

[summer blizzard]

I must say that i am more than convinced now of a large eruption going to occur (VEI4+). The fact that we saw an event about 7km away at around 900m followed by greater harmonic tremors but with activity moving closer to the island and less than 600m just offshore last night does indicate that the earthquake indicates a blockage on the island (not unusual being dormant for 200+ years) and now we seemingly see no activity.

I strongly suspect now that there will be another large earthquake at some point with a very big eruption. Given that magma has also moved along a fault i would not be surprised if water enters the magma chamber and this eruption gets massive.

In summary guys, i am leaning towards Montserrat mark 2.

Do we know what has been said at the press conference.

this the  latest  i can find

Current Volcanic Islands (AVCAN)

Impressive tremor, we know from where it broke, it seems the news conference PEVOLCA confirmed eruptive process in place at two different points by the presence of two spots in the sea, with a strong sulfur smell and appearance of dead fish. The distance of the ongoing eruption of the Restinga area 1 - eruptive mouth: 5.5 - 7 miles - 970-1000 m deep ... See more

    d

    2 - eruptive mouth: 2 - 2.5 miles - 700 m depth

    3 - eruptive mouth: 1 - 1.5 miles - 500 m deep The question is, will continue to approach the island?. In the 1 have left images, I guess in the news in a few minutes more will not lose them ... (Enrique).

   

this the  latest  i can find

Current Volcanic Islands (AVCAN)

Impressive tremor, we know from where it broke, it seems the news conference PEVOLCA confirmed eruptive process in place at two different points by the presence of two spots in the sea, with a strong sulfur smell and appearance of dead fish. The distance of the ongoing eruption of the Restinga area 1 - eruptive mouth: 5.5 - 7 miles - 970-1000 m deep ... See more

    d

    2 - eruptive mouth: 2 - 2.5 miles - 700 m depth

    3 - eruptive mouth: 1 - 1.5 miles - 500 m deep The question is, will continue to approach the island?. In the 1 have left images, I guess in the news in a few minutes more will not lose them ... (Enrique).

   

Tiny, given that there have been 3 vents which at the very least have allowed gas out do you think that enough pressure has been released to prevent an eruption on the island or would you agree with my opinion which is that since harmonic tremors actually increased during the eruptions, the door has mearly been opened and a much larger one is on the way.

Edited October 12, 2011 by summer blizzard

[tinybill]

pass i only found this on a facebook page just have to wait and see i surprised sky has not picked this up yet

[summer blizzard]

Just realized, do we know the epicenter of the earthquake which occurred before activity stopped. Is it closer to the island than the 3rd eruption mouth.

[The PIT]

I'd be surprised that there would be a huge eruption. They tend to be rare at hot spot volcano's, not saying they can't occur it's happened on Hawaii in the past. Also depends on whether the vents open close enough to the surface to the sea surface or just slightly above where interaction with the sea can cause Surtseyan type explosive activity.

Montserrat is a subduction type of volcano with dome building and very viscous lava which tends to leads to explosive eruptions.

[summer blizzard]

Can El Hierro still be classed as a hot spot volcano given that it has not erupted for over 200 years?

[Paranoid]

Hot spot refers to the plume of magma that feeds it (usually they are responsible for volcanoes that are well away from plate boundaries, like Hawaii.) and not the activity of the volcano. Yellowstone is a hotspot volcano and that erupts every 640,000 years, which also goes to show that hot spot volcanoes do not always have effusive eruptions, although it does seem to be more common than explosive ones. If anyone knows that type of lava that has previously been erupted at El Hierro then you can get an idea of what sort of eruption will occur.

Edited October 12, 2011 by Paranoid

[The PIT]

Canary islands are considered hot spot volcano's. It also the youngest of the islands so perhaps we shouldn't be surprised at renewed activity.

Hot spot refers to the plume of magma that feeds it (usually they are responsible for volcanoes that are well away from plate boundaries, like Hawaii.) and not the activity of the volcano. Yellowstone is a hotspot volcano and that erupts every 640,000 years, which also goes to show that hot spot volcanoes do not always have effusive eruptions, although it does seem to be more common than explosive ones. If anyone knows that type of lava that has previously been erupted at El Hierro then you can get an idea of what sort of eruption will occur.

From GVP

The subaerial portion of the volcano consists of flat-lying Quaternary basaltic and trachybasaltic lava flows

[Paranoid]

Ah, basaltic lavas usually come from less explosive eruptions, although if any water intrusions happen that can cause some quite powerful eruptions like we saw with Eyjafjallakjokull last year and possibly with Grimsvotn earlier this year.

[summer blizzard]

Hot spot refers to the plume of magma that feeds it (usually they are responsible for volcanoes that are well away from plate boundaries, like Hawaii.) and not the activity of the volcano. Yellowstone is a hotspot volcano and that erupts every 640,000 years, which also goes to show that hot spot volcanoes do not always have effusive eruptions, although it does seem to be more common than explosive ones. If anyone knows that type of lava that has previously been erupted at El Hierro then you can get an idea of what sort of eruption will occur.

Hot spot refers to the plume of magma that feeds it (usually they are responsible for volcanoes that are well away from plate boundaries, like Hawaii.) and not the activity of the volcano. Yellowstone is a hotspot volcano and that erupts every 640,000 years, which also goes to show that hot spot volcanoes do not always have effusive eruptions, although it does seem to be more common than explosive ones. If anyone knows that type of lava that has previously been erupted at El Hierro then you can get an idea of what sort of eruption will occur.

Quaternary basaltic and trachybasaltic.

Good stuff or the boring stuff?

[Paranoid]

It probably all depends really on the internal pressures and dissolved gases within the magma, but basaltic lavas are certainly capable of producing VEI 3-4 eruptions. I can't claim to be an expert though, and also as far as i know there is only one historical eruption at El Hierro so i'm not sure what to expect exactly (epic vulcanology cliche).

Found this on the basalt page on wikipedia:

"Basalt which erupts under open air (that is, subaerially) forms three distinct types of lava or volcanic deposits: scoria; ash or cinder (breccia); and lava flows.

Basalt in the tops of subaerial lava flows and cinder cones will often be highly vesiculated, imparting a lightweight "frothy" texture to the rock. Basaltic cinders are often red, coloured by oxidized iron from weathered iron-rich minerals such as pyroxene.

`A`a types of blocky, cinder and breccia flows of thick, viscous basaltic lava are common in Hawaii. Pahoehoe is a highly fluid, hot form of basalt which tends to form thin aprons of molten lava which fill up hollows and sometimes forms lava lakes. Lava tubes are common features of pahoehoe eruptions.

Basaltic tuff or pyroclastic rocks are rare but not unknown. Usually basalt is too hot and fluid to build up sufficient pressure to form explosive lava eruptions but occasionally this will happen by trapping of the lava within the volcanic throat and build up of volcanic gases. Hawaii's Mauna Loa volcano erupted in this way in the 19th century, as did Mount Tarawera, New Zealand in its violent 1886 eruption. Maar volcanoes are typical of small basalt tuffs, formed by explosive eruption of basalt through the crust, forming an apron of mixed basalt and wall rock breccia and a fan of basalt tuff further out from the volcano."

Edited October 12, 2011 by Paranoid

[Crepuscular Ray]

It appears to have a mix. There are basaltic flows at lower levels but cinder cones on the tops, where more recent activity has taken place.\

Edit: What he said!

Edited October 12, 2011 by crepuscular ray

[yamkin]

Low magnitude tremors at El Hierro this evening 12.10.11

[summer blizzard]

Quaternary basaltic and trachybasaltic tuff if that makes a difference (i had no idea what tuff was).

The activity has been occuring from quite far out where the basaltic deposits are, so i am wondering if this is the magma being enfused at the moment.

Does the quaternary or trachybasaltic element make a difference.

[Paranoid]

Yeah, i've been having a look at the island and it doesn't look like a shield volcano, and the cinder cones suggest it's not exactly a stratovolcano so i don't think a large explosive eruption will be as likely to occur. Anything within the range of VEI 1-3 is possible i'd say, as it's unlikely to be entirely effusive or explosive. A small to moderate eruption column accompanied by some lava flows is my best bet.

@ SB: Quaternary merely refers to the period in which it was erupted (within the last 2.5 million years roughly) and trachybasaltic rock is a combination of trachyite and basalt, which are both from fairly non-viscous lavas, like those at Hawaii but probably not quite as runny. Tuff is a rock formed by accumulated volcanic ash (evidence of some explosive activity).

Edited October 12, 2011 by Paranoid

[summer blizzard]

Low magnitude tremors at El Hierro this evening 12.10.11

Do we know how close they are.