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General Chat / Random Musings - 2021


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Well at least we know why Len's not been about for a while.   https://www.ladbible.com/news/uk-depraved-man-who-had-sex-with-chickens-has-jail-term-reduced-20210130?source=facebook&fbclid=IwA

Nice one Downzy. It's about time as I once snogged one of the posters on the first page of the last General Chat and it has constantly haunted me. 

Nice one Downzy. It's about time as I once snogged one of the posters on the first page of the last General Chat and it has constantly haunted me. :lol:

Edited by Gracii Guns
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16 minutes ago, Gracii Guns said:

Nice one Downzy. It's about time as I once snogged one of the posters on the first page of the last General Chat and it has constantly haunted me. :lol:

... aren't you making people remember now, on the first page of the new thread? :P

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14 minutes ago, Gracii Guns said:

Yes, but it wasn't exactly last week, I'm happy to laugh at myself.

that's the spirit!

self-relativation is the mark of a good character

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4 hours ago, Gracii Guns said:

Nice one Downzy. It's about time as I once snogged one of the posters on the first page of the last General Chat and it has constantly haunted me. :lol:

That bad were they? lmao

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3 hours ago, Gracii Guns said:

Yes, but it wasn't exactly last week, I'm happy to laugh at myself.

The old thread is only halfway down the page. I've got it narrowed down to 3 suspects so far. :lol: 

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10 hours ago, Dazey said:

The old thread is only halfway down the page. I've got it narrowed down to 3 suspects so far. :lol: 

And what have you deduced so far watson? 

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42 minutes ago, lukepowell1988 said:

Think my farts could help North Korea reach the dream of nukes

If North Korea didn’t mind constantly finding shitty undies in a bush. 

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1 hour ago, lukepowell1988 said:

Think my farts could help North Korea reach the dream of nukes

 

30 minutes ago, Dazey said:

If North Korea didn’t mind constantly finding shitty undies in a bush. 

Oh come on!  it's the first bloody page!

Luke's smelly shitty arse needs to wait until at least a late Feb/page 5 or six. 

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Just now, spunko12345 said:

 

Oh come on!  it's the first bloody page!

Luke's smelly shitty arse needs to wait until at least a late Feb/page 5 or six. 

Surely the fact that Luke’s smelly, shitty arse can’t wait is exactly the point. :lol: 

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6 hours ago, Graeme said:

Image

Sicily right now, Mount Etna doing her thing. Wish I was there, in a world without Covid.

Why? What on earth could you have done? Plugged the hole with your enormous ego? Face it, volcanoes rule this earth and there is nothing we can do about it.

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38 minutes ago, SoulMonster said:

Why? What on earth could you have done? Plugged the hole with your enormous ego? Face it, volcanoes rule this earth and there is nothing we can do about it.

Oh no, just to watch :) these kinds of eruptions at Etna aren't typically a threat to anyone unless they go looking for trouble. It has other eruptions at times that are more severe, but the hazards in these frequent, small paroxysms tends to be localised around the summit craters, so unless you climb up to the top (which is prohibited by law when the activity is high) then you can watch from the surrounds in peace and wonderment!

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17 minutes ago, Graeme said:

Oh no, just to watch :) these kinds of eruptions at Etna aren't typically a threat to anyone unless they go looking for trouble. It has other eruptions at times that are more severe, but the hazards in these frequent, small paroxysms tends to be localised around the summit craters, so unless you climb up to the top (which is prohibited by law when the activity is high) then you can watch from the surrounds in peace and wonderment!

How can you exclude the possibility of an eruption further below the summit spilling hot burning lava over all the Italians? Or just a good scolding with hot ash? Seem perilous when you look at that photo. 

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9 hours ago, SoulMonster said:

How can you exclude the possibility of an eruption further below the summit spilling hot burning lava over all the Italians? Or just a good scolding with hot ash? Seem perilous when you look at that photo. 

I mentioned that it's a possibility, I just clarified that's not what's happening at the moment :P... and if it was going to happen then I'm confident that the volcanologists at the Istituto Nazionale di Geofisica e Vulcanologia would pick up the signs.

The ash in that cloud in the photo will be cold long before it settles, at worst it will be a thin layer for people to wipe off the top of their cars. Notice the cloud isn't very high above the crater? That's because there's not a lot of explosive power in the eruption - the magma here is very hot and runny, so the dissolved gasses can easily escape. You can see in this video it's just a (relatively) gentle fountain of larger globules of lava:

 

We're not getting the pressurised jet of gas required to pulverise the magma into fine particles and carry the ash tens of kilometres above the crater, whilst keeping the interior of the ash cloud hot. Here's an example of what that looks like when it happens at the same volcano:

Volcano Photo of the Week - by Giuseppe Famiani: Etna's paroxysm from  Voragine crater on 4 Dec 2015, seen from Cesarò / VolcanoDiscovery

Even that eruption, which was several orders of magnitude bigger than what's happening right now, wasn't really a danger to people in the surrounds because Etna's a huge volcano and the summit crater's a fair distance from any towns. It is capable of eruptions tens of times larger (and they would be terrifying) but the last time one of those happened was more than 2,000 years ago!

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1 minute ago, Graeme said:

I mentioned that it's a possibility, I just clarified that's not what's happening at the moment :P... and if it was going to happen then I'm confident that the volcanologists at the Istituto Nazionale di Geofisica e Vulcanologia would pick up the signs.

The ash in that cloud in the photo will be cold long before it settles, at worst it will be a thin layer for people to wipe off the top of their cars. Notice the cloud isn't very high above the crater? That's because there's not a lot of explosive power in the eruption - the magma here is very hot and runny, so the dissolved gasses can easily escape. You can see in this video it's just a (relatively) gentle fountain of larger globules of lava:

 

We're not getting the pressurised jet of gas required to pulverise the magma into fine particles and carry the ash tens of kilometres above the crater, whilst keeping the interior of the ash cloud hot. Here's an example of what that looks like when it happens at the same volcano:

Volcano Photo of the Week - by Giuseppe Famiani: Etna's paroxysm from  Voragine crater on 4 Dec 2015, seen from Cesarò / VolcanoDiscovery

Even that eruption, which was several orders of magnitude bigger than what's happening right now, wasn't really a danger to people in the surrounds because Etna's a huge volcano and the summit crater's a fair distance from any towns. It is capable of eruptions tens of times larger (and they would be terrifying) but the last time one of those happened was more than 2,000 years ago!

That's an awesome photo.

What are the signs of a larger, more destructive eruption? More shaking leading up to it? Particular rumblings that can be monitored?  Fissures and cracks opening up further down?

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On 1/19/2021 at 6:12 PM, SoulMonster said:

That's an awesome photo.

What are the signs of a larger, more destructive eruption? More shaking leading up to it? Particular rumblings that can be monitored?  Fissures and cracks opening up further down?

There can be various! Volcanic earthquakes are usually a good indicator that magma is moving underground. If you have more than three seismometers then you should be able to triangulate the location of volcano-seismic events, and that will tell you whereabouts within the volcanic system they're occurring, so you can get some indication if activity is progressing towards the surface. Also, because the seismic signals move more slowly through magma than solid rock, you can also make a rough estimate of the size of a subterranean body of magma - so that can help give an idea of the potential size of an eruption, if you can estimate quantity of magma that's rising.

When rock is fractured by moving magma, it creates 'volcano-tectonic' earthquakes. These can happen without resulting in an eruption, the magma can just be sloshing about underground, but if you see a sequence of strong, frequent volcano-tectonic earthquakes progressing towards the surface then there's a strong chance you're looking at precursors to an eruption.

There's another type of volcano seismicity that's proven to be really important as well, they're known as 'Type B' or 'Long Period' events, and they're indicative of the pressurised movement of gasses within a volcanic system (it's the same waveform you'd see analysing the sonic signal from a pipe organ, where the sound is generated by air being funnelled through the pipes). Even when volcanoes aren't erupting, gasses from the magma can make their way up through systems of cracks and emerge at the surface from vents called 'fumaroles', or through volcanic hot springs/geysers if there's a layer of groundwater for them to pass through. These gasses, if analysed, can tell volcanologists about the chemical composition of the source magmas, which can give an idea about how explosive we might expect them to be. Also, sometimes there's a pretty straightforward relationship between the amount of gas being emitted and the magmatic conditions below the surface (i.e. more gas = more magma and it's closer to the surface), but this isn't always the case, and this is why Long Period earthquakes are important... In the early 1990s, there was a big debate among the gas geochemists in volcanology and the seismologists - the gas guys basically argued that you couldn't have an eruption without precursory gas emissions. However, it's since been shown that in scenarios where there isn't a lot of gas being emitted, you should look for Long Period seismic signals, and if you see a lot of those, that means the gas is getting pressurised with no escape route, so you're likely to see a very violent explosion.

That doesn't necessarily mean a 'big' eruption; magnitude and intensity are two different parameters, you can have a big, gentle eruption and a small, violent one, so the other variables are very important to look at in order to get a better idea of if you're potentially dealing with a worst-case scenario (i.e. a big, violent eruption). You can also use tiltmeters or INSAR to measure changes in elevation around a volcano. The ground level can rise if a volcano is being inflated with a body of magma, and this can give you an idea of how big the eruption might be. This image from Mount Saint Helens in 1980 is a good example, where the magma created an enormous bulge on the side of the volcano that showed the volcanologists (who were witnessing this for the first time) that they were potentially dealing with something big...

Bulge on the north side of Mount St. Helens developed as magma push...

Alternatively, in some volcanoes, deflation can be an indicator that a previously emplaced body of magma has found somewhere else to go, like this timelapse of the summit of Kilauea volcano in Hawaii from 2018, when the lava lake at the summit drained and a large part of the summit collapsed as the magma escaped through a fissure on the flank of the volcano (shown conveniently at the end of the clip).

The important thing is, wherever possible, not to take any of these things in isolation as an indicator of what the volcano is going to do, but always to try to cross-reference with other variables! I hope that helps!

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