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MKN

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Posted
  • Location: Mytholmroyd, West Yorks.......
  • Weather Preferences: Hot & Sunny, Cold & Snowy
  • Location: Mytholmroyd, West Yorks.......

I'm sorry things have descended into bickering again. Mackerel, don't forget how 'the great and the good' received the first attempts to bring plate tectonics into the fold. Though there may be 'intellectual safety' in numbers it doesn't always pay to follow blindly.

Svalbard's quake (and whatever promoted that) had probably a part to play in the final stresses leading to the release but whose to say that the 'straw' that broke this camels back wasn't the added 'G's from moon and sun??

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Posted
  • Location: Rushden, East Northamptonshire
  • Location: Rushden, East Northamptonshire
What is the difference between the European Macroseismic scale and the Richter scale by the way???

Its based on the felt effects, rather than the actual measured amplitude. The questionnaire which is on the BGS site forms the basis of the macroseismic survey from the public's response. I suppose an analogy might be that of the Beaufort scale - i.e. Force 6 = Strong Breeze = Large branches in motion; whistling heard in telegraph wires; umbrellas used with difficulty etc.

Edited by mackerel sky
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Posted
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield
  • Weather Preferences: Any Extreme
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield
Its based on the felt effects, rather than the actual measured amplitude. The questionnaire which is on the BGS site forms the basis of the macroseismic survey from the public's response. I suppose an analogy might be that of the Beaufort scale - i.e. Force 6 = Strong Breeze = Large branches in motion; whistling heard in telegraph wires; umbrellas used with difficulty etc.

So a 5.2 on the ML scale is nothing to do with a 5.2 on the Richter scale which seems to be the way it was reported.

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Posted
  • Location: Rushden, East Northamptonshire
  • Location: Rushden, East Northamptonshire
So a 5.2 on the ML scale is nothing to do with a 5.2 on the Richter scale which seems to be the way it was reported.

ML stands for local magnitude which is indentical to the Richter scale. No one really inside seismology refers to the Richter scale. The magnitude is given by

Ml = a log(10) * Amplitude + b log(10) * Distance + c * distance + d

Amplitude is the maximum zero-peak ground displacement measured on the seismogram, distance is the hypocentral distance in km and a, b, c and d are constants. The default constants are for California, I must point out.

The local magnitude is generally ONLY calculated for distances upto ~ 1500 km and periods of less than 5 seconds. At greater distances than this the body wave magnitude (Mb) tends to be used instead. This is why for example, the USGS will always produce a magnitude figure different to the the BGS.

The European Macroseismic Scale (EMS) is not directly related to the local or Richter magnitude. I suppose a better analogy is the type of scheme Torro uses, because our Tornadoes are much smaller.

Edited by mackerel sky
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Posted
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield
  • Weather Preferences: Any Extreme
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield
ML stands for local magnitude which is indentical to the Richter scale. No one really inside seismology refers to the Richter scale. The magnitude is given by

Ml = a log(10) * Amplitude + b log(10) * Distance + c * distance + d

Amplitude is the maximum zero-peak ground displacement measured on the seismogram, distance is the hypocentral distance in km and a, b, c and d are constants. The default constants are for California, I must point out.

The local magnitude is generally ONLY calculated for distances upto ~ 1500 km and periods of less than 5 seconds. At greater distances than this the body wave magnitude (Mb) tends to be used instead. This is why for example, the USGS will always produce a magnitude figure different to the the BGS.

The European Macroseismic Scale (EMS) is not directly related to the local or Richter magnitude. I suppose a better analogy is the type of scheme Torro uses, because our Tornadoes are much smaller.

Well using the EMS certainly will cause some confusion. To me it feels the Europeans just doing something different for the sake of it and we're following suit. Really need one standard and stick to it. Thanks for your reply though.

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Posted
  • Location: Atherstone on Stour: 160ft asl
  • Location: Atherstone on Stour: 160ft asl

Well it's been 2 days now and still no word from Pakistan about them setting up a "Quake Appeal" for the devastated people of Lincolnshire.

Next time they have one, they can b*gger off, they'll not get a penny from me !! :D

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Posted
  • Location: Eastbourne, East Sussex (work in Mid Sussex)
  • Location: Eastbourne, East Sussex (work in Mid Sussex)

URGENT - LINCOLNSHIRE EARTHQUAKE APPEAL

At 00:58 on Wednesday, 27 February 2008 an earthquake measuring 5.3 on the richter scale hit Lincolnshire causing untold disruption and distress

Many were woken well before their giro arrived

Several priceless collections of mementos from the Balearics and Spanish costas were damaged

Three areas of historic and scientifically significant litter were disturbed

Thousands are confused and bewildered, trying to come to terms with the fact that something interesting has happened in Lincolnshire

HOW YOU CAN HELP

£2 buys chips, scraps and blue pop for a family of four

£10 can take a family to Grimsby for the day, where children can play on an unspoiled canal bank among the national collection of stinging nettles

22p buys a biro for filling in a spurious compensation claim

PLEASE ACT NOW

Simply pm me by return with your credit card details and I'll do the rest

Edited by Coast
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Posted
  • Location: 4 miles north of Durham City
  • Location: 4 miles north of Durham City
URGENT - LINCOLNSHIRE EARTHQUAKE APPEAL

At 00:58 on Wednesday, 27 February 2008 an earthquake measuring 5.3 on the richter scale hit Lincolnshire causing untold disruption and distress

Many were woken well before their giro arrived

Several priceless collections of mementos from the Balearics and Spanish costas were damaged

Three areas of historic and scientifically significant litter were disturbed

Thousands are confused and bewildered, trying to come to terms with the fact that something interesting has happened in Lincolnshire

HOW YOU CAN HELP

£2 buys chips, scraps and blue pop for a family of four

£10 can take a family to Grimsby for the day, where children can play on an unspoiled canal bank among the national collection of stinging nettles

22p buys a biro for filling in a spurious compensation claim

PLEASE ACT NOW

Simply pm me by return with your credit card details and I'll do the rest

Heh.

There was a similar message doing the work email rounds after the summer floods in Hull. It was rather mocking to say the least.

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Posted
  • Location: Eastbourne, East Sussex (work in Mid Sussex)
  • Location: Eastbourne, East Sussex (work in Mid Sussex)
7076.jpg
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Posted
  • Location: Saddleworth, Oldham , 175m asl
  • Weather Preferences: warm and sunny, thunderstorms, frost, fog, snow, windstorms
  • Location: Saddleworth, Oldham , 175m asl

I was wondering is there a map anywhere that shows where faults are in the British Isles?

Edited by James M
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Posted
  • Location: Irlam
  • Location: Irlam
Largest instrumentally recorded earthquake was a magnitude 6.0 (local or richter magnitude) in the Dogger Bank 1931 I think. That was felt widely in eastern england, but as you can imagine it happened well offshore. Largest instrumentally recorded earthquake onshore was on the 19th July 1984 local magnitude 5.4 on the Lleyn Pennisula.

It was 6.1 on the Richter scale. I forgot I had got a copy of the Times of the day with the article on this tremor. It was felt right across large parts of Great Britain. It actually split the head of the waxwork figure of Crippen at Madame Tussaud's. :D I'll post it sometime. ;)

Edited by Mr_Data
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  • 2 weeks later...
Posted
  • Location: Rushden, East Northamptonshire
  • Location: Rushden, East Northamptonshire
I was wondering is there a map anywhere that shows where faults are in the British Isles?

Rather late in the day, but if you go back to page 5 of this thread I posted a map I'd created with the earthquakes i've been using superimposed with the all the faults and main structural elements. The black lines are the major Paleozoic terrane boundaries... essentially all the bits and pieces that came together to form the UK as we now know it.

Edited by mackerel sky
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Posted
  • Location: Western Isle of Wight
  • Weather Preferences: Snow, Storm, anything loud and dramatic.
  • Location: Western Isle of Wight

The BGS site has not been updated yet, but there was a Mag 3 in the Dover straights yesterday.

Here it is on the EMSC site http://www.emsc-csem.org/index.php?page=cu...il&id=81008

Russ

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It can take a couple of days to update with some quakes as they check that the readings weren't caused by bomb disposal or a sonic boom before they put it up.

The after shocks from 5.2 took 3 or 4 days before they were all on there.

I'll have to take a closer look at the EMSC site, not had chance yet. ;)

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