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Whose fault is it? (Geophysics)
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Pulp History


In: Wales
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Regarding the latest earthquake in England..... apparently we now lie over 'old' fault lines which are still (sometimes) active?? What?? I thought the fault lines were fixed? How can they have moved? Why do the 'experts' say that England and Scotland were once on different plates but are both now in the middle of one?? If the faults are old then why are they still 'going off'?? I am obviously so ignorant on these matters!!! Maybe I'm not the only one!
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AJMorton



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Well I will give you some solidarity in ignorance:

Is it weird or normal for one quake, based in the south-east of England to be felt so strongly in every county of the UK?

That seems large to me.
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Mick Harper
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In: London
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No Applied Epistemologist believes in Plate Tectonics.
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Pulp History


In: Wales
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Agreed, Mick, but how would orthodoxy explain the quake in England?? I mean - I was never taught about 'old fault lines' going off!!
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Mick Harper
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In: London
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They use a rather elegant procedure that is guaranteed to be always right. It proceeds like this.
1. Wherever you know earthquakes take place, draw a line through them and declare this to be a plate boundary.
2. Now, whenever one of these earthquakes happen, you have further proof of your theory.
3. When an earthquake happens anywhere else, somewhere not on a plate boundary, then re-draw the nearest boundary to encompass the new earthquake, explaining that Plate Tectonics is an uncertain science that needs constant refining as further data comes in.
4. If there is no boundary convenient, then just draw in a completely fresh boundary, thereby creating a completely new plate (plates can be any size so one big one can be broken up many times using this process).
5. But if the process has gone so far that the plates are starting to look a little bit...um...arbitrary, then use a dotted line to cover the earthquake and declare the existence of a platelet. (What the hell, the punters will swallow anything!)
6. If even the platelet dodge is looking a bit dodgy, then just declare "a local zone of weakness" or some other official sounding version of "Don't Know".
7. In real extremis, just say, "Don't know". Everyone loves an expert who is prepared to hold his hand up and admit that The Greatest Prime Mover On Earth has its secrets even from us.
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Komorikid


In: Gold Coast, Australia
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In real extremis, just say, "Don't know". Everyone loves an expert who is prepared to hold his hand up and admit that The Greatest Prime Mover On Earth has its secrets even from us.

The secret to Earthquakes is 'As Above So Below'. An Earthquake is Lightning and the Aftershock is Thunder.
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Chad


In: Ramsbottom
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Hi Folks. I'm rather new to this forum stuff, so you may have to bear with me while I stumble along.

On the subject of earthquakes in England, does anybody remember the 'swarm' of quakes which hit Manchester in 2002? - There were about 120 over a period of 3 months, all having their epicenters in the vicinity of the new City of Manchester Stadium.

Now, members of my family have lived in that part of the city, for many generations. So I knew it had been a coal mining area up until the 1960s, and wondered if there was a connection.

Digging deeper, - forgive the bad pun -- it turns out that the area had been extensively mined for coal since at least the Tudor period and even in the early 1600s it was outputting over 10,000 tons per year.

Surely, I thought, the construction of the 'Sportcity' complex - for the 2002 Commonwealth Games, on top of this honeycomb - and the subsequent earthquake swarm, later that same year, were more than mere coincidence.

But no, I was completely wrong. The two were completely unconnected. It was all down to perfectly natural seismic activity, on a previously inactive geological fault.

My arse!
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Rocky



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Here's an article about the top 5 ways to cause an earthquake:

http://blog.wired.com/wiredscience/2008/06/top-5-ways-that.html

The author believes in plate tectonics though.
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Mick Harper
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In: London
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So pile-driving for the footie stadium plus palaeo-coalmines would certainly account for it. The wider point of course is that now we know what tiddly forces can create earthquakes, the official explanation -- that it is titanic plates rubbing against one another -- is out of court simply as a matter of scale.

If Francis Lee diving can cause a judder then it follows that earth-shattering tectonic events should be occurring everywhere and everywhen. If there are moving plates of course....
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Chad


In: Ramsbottom
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Thanks for that link Rocky - most interesting. - Pity nobody from the British Geological Survey has read the article.

Oh and Mick..... Francis Lee???........ bloody hell........ are you really that old?
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Hatty
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In: Berkshire
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Has there been a noticeable increase in seismic activity since the advent of industrialisation as in the dynamiting of rock to construct railway tunnels or dams?
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Mick Harper
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In: London
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No, no, I'm in my mid-twenties. I was merely mentioning something that might have happened in the sixties to coincide with your parents' earthquake experiences. Franny Lee, Joe Mercer, the traitor Law....these are but encyclopaedic facts I require as a fully operant polymath.
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Chad


In: Ramsbottom
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Whereas I, being a fully operant monomath, have no such encumbrances.

I do however have vague recollections of standing on the terraces at Old Trafford in my youth, cheering on Charlton, Best and Co. but since I am, like you Mike, barely in my mid-twenties, this can be nothing more than a residual memory from a previous incarnation.

But back to earthquakes.

I remember reading at the time that the Manchester Swarm was not unique in the U.K. and there had been previous instances in Wales and I think Scotland ... I forget the exact locations, ..... but what's the betting they were also in coal mining areas!

And over on the BGS website, the report on the events in Manchester contains a paragraph on the local geology. It mentions the fact that the area is in the southern part of the extensively mined Lancashire coal field, but fails to attach any relevance to this and seems to concentrate more on the proximity -- some miles to the south -- of the 'heavily faulted' Cheshire Basin.

That got me thinking ..... why should the Cheshire Basin be 'heavily faulted'?

Couldn't have anything to do with all that salt mining ....... Could it?
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Mick Harper
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In: London
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Probably not modern saltmining since (as I understand it) they force in an equivalent amount of liquid to compensate for the brine they take out. But on one of our other threads there's a discussion about the antiquity of the Cheshire salt industry (eg how old is Nantwich) so this might not apply.

The interesting thing about coalmining (even quite modern coalmining) is that they use wooden pit props and then, when mining ends, flood the pit. This is tantamount to recreating the way they used to bring down castle walls, on the grand scale but over the long haul. So, given the depth and intricacy of mine tunnels, the tensions probably build up at various places as props fail until, crack, we have ourselves an earthquake. The shallow stuff just causes surface subsidence of course.
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Chad


In: Ramsbottom
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Found this little snippet on salt mining in Northwich, Cheshire:

"During the 1800s, salt mining brought prosperity and employment to Northwich, swelling its population from less than 1,500 to more than 15,000. However, the industry also created huge, unstable underground caverns. Back then, shops, houses and even whole streets would regularly collapse. Indeed, the town's rickety, cockeyed buildings became something of a tourist attraction during the Victorian era as visitors flocked to see what was..."

Wish I could figure out how to format the text and use quote boxes................................where's that laboratory chimp when you need him?
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