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Offline ukmicky

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earthquake
« on: 28/04/2007 22:34:56 »
We all know what causes earthquakes its geological faults the comong together of two tectonic plates.

So why did the UK today have an earthquake that registered 5 on the richter scale ,does the uk have fault lines running under it or was there another cause


 

Offline Seany

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« Reply #1 on: 28/04/2007 22:45:30 »
There was an earthquake in UK TODAY? Wow, I'm late on news!
 

Offline Bass

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« Reply #2 on: 29/04/2007 00:11:47 »
There are fault lines everywhere.  Most are no longer active, or are active only infrequently- except along active tectonic zones (plate margins, hot spots, etc.)  An earthquake is basically a mechanism to relieve strain in the crust- the strain may not be directly related to plate tectonics (for example, loading or isostatic rebound).  Probably the largest earthquake in recorded U.S. history was located in the Mississippi Valley, far from present plate boundaries.
 

Offline JimBob

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« Reply #3 on: 30/04/2007 00:39:57 »
What a coincidence! Day before yesterday after watching Edward II, Marlow's play, on the television, I looked up the Earl of Cornwall, Piers Gaveston, who was executed at a quaintly named place called Leek Wootton, just north of Warwick.

Wikipedia has this to say:

"The barons grew resentful of Gaveston and twice insisted on his banishment. On each occasion Edward recalled his friend, whereupon the barons headed by the king's cousin Thomas, Earl of Lancaster went to war against king and his favourite. In 1312, Gaveston was executed as a traitor by the Earl of Lancaster and his allies, who claimed that Gaveston led the King to folly. Gaveston was run through and beheaded on Blacklow Hill, outside the small village of Leek Wootton, where a monument (Gaveston's Cross) still stands today."

THE POINT IS: When I looked up Leek Wootton on Google Earth I found out that on Sept. 23, 2000 there was a 4.2 magnitude earthquake centered .85 miles west of Warwick, UK and about 2 miles SW of Leek Wootton.  I was interested in WHY such a thing happened and started looking. It seems that in a crescent, concave to the west, from the mouth of the Severn to the mouth of the Tees (actually from west of Lyme Regis) there is the hinge-line of the Thames Basin. That is the earth goes from being (in this case) pushed up to being down-warped. This downwarp is the valley Tames. On the geologic map of the UK (http://i38.photobucket.com/albums/e111/geezer69/ukGEOmap8.jpg) the west edge of the olive green is about the same as the hinge line.   

A hinge line is potentially unstable. The forces that opened the Atlantic Ocean also opened the Tames basin and the Paris Basin (geologic map of Europe at http://i38.photobucket.com/albums/e111/geezer69/Geology_euro.jpg ). Since these forces are still active - The Atlantic Ocean is opening - they are being applied to the islands of the UK and Ireland right now and this causes the earth to need to relieve the compressive stress. An earthquake is the solution to the compressive stress.

On the map of the UK the basin is all the greens, yellows and browns (later numbered 3, 4, 5 & 6) and on the Europe map the blue, the greens, yellows and pink are the sedimentary basins that have been formed since the Atlantic stated opening and Africa began running into Europe.

 

Offline ukmicky

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earthquake
« Reply #4 on: 30/04/2007 02:13:38 »
Cheers  Bass and Jimbob that was  a bit of coincidence but also brilliant thankyou very much

I liked the maps of the UK showing the geology and then how when you look at the rest of eroupe  it clearly shows how similar the geology is at the points where the UK use to be joined up.
« Last Edit: 30/04/2007 02:17:14 by ukmicky »
 

Offline JimBob

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« Reply #5 on: 01/05/2007 01:20:07 »
Thanks, Micky

 8)  [:I]
 

Offline ichnos

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« Reply #6 on: 01/05/2007 12:05:49 »
earthquakes are not only fault related but can be associated with large land slides and volcanic eruptions as gas/magma builds up below the surface (probably not in this case!) I'm not sure what the exact cause was, it would depend on the depth of the 'quake. If it is deep and tectonically related it is probably to do with the fault reactivation associated with the Alpine orogeny.. there are loads of Alpine collision related faults along the south coast and channel. :-)
 

another_someone

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earthquake
« Reply #7 on: 01/05/2007 16:41:35 »
http://www.earthquakes.bgs.ac.uk/recent_events/uk_special/alert_info_uk.htm
Quote
The following preliminary information is available for this earthquake:

DATE : 28 April 2007
ORIGIN TIME : 07:18 10.0s UTC
LAT/LONG : 50.97 North / 1.38 East
GRID REF : 636.9 kmE / 124.4 kmN
DEPTH : 5.0 km
MAGNITUDE : 4.3 ML
INTENSITY : 6 EMS
LOCALITY : Dover Straits, 14km south of Dover

This is the largest event detected in the region since a magnitude 4.4 ML earthquake in 1950. Large earthquakes have also occurred in the region in the historical past in 1382 (magnitude 5.8), 1580 (magnitude 5.8) and 1776 (magnitude 4.1).

Elsewhere, the 1580 quake is estimated at 20-25Km depth.
 

Offline Yousaf

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« Reply #8 on: 04/11/2007 12:45:48 »
Hi i want to know that is earthquake can change brown coler of mountains into white mountains ? after Mw 7.6 Kashmir earthquake in 2005, some of big moutains coler changed into  totally white!is there any other example? here is google map link u can see by ur self
newbielink:http://maps.google.com/maps?f=q&hl=en&geocode=&time=&date=&ttype=&q=azad+kashmir&sll=33.979809,76.552734&sspn=4.518041,7.404785&ie=UTF8&ll=34.393109,73.482517&spn=0.002196,0.005375&t=h&z=18&om=1 [nonactive]
and here wikipedia artical on Kashmir earthquake2005
newbielink:http://en.wikipedia.org/wiki/2005_Kashmir_earthquake [nonactive]

« Last Edit: 04/11/2007 12:59:27 by Yousaf »
 

Offline JimBob

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« Reply #9 on: 04/11/2007 17:58:12 »
Yousaf,

Thank you for joining and asking this question. Welcome!

The earthquake in 2005 shook the ground so hard that rocks came apart and slid down the valley the river runs in. The white color is the color of the rock when it is freshly broken. As it sits on the ground for years and years, a process called "weathering" takes place. It causes chemical changes that make the rock get darker.

It is the same when you buy a new copper pot or tray. It is shinny and looks very nice. But if it gets broken and is thrown out it will turn green over a long time.

On Google maps, the darker the rocks you see are, the longer the surface has been stable. The whiter they get, the newer the surface.


 

Offline Alandriel

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« Reply #10 on: 04/11/2007 21:42:45 »
Perhaps I can cite another example for Yousaf.

In 1995 we had a 7.2 quake just off Nuweiba in the Red Sea / Egypt.
Threw me out of bed that one, I was some 150km away.  ::).... and did quite a bit of local damage

Unfortunately a lot of developement has gone since along the Red Sea coast (and time has passed) but I think you can still see quite a good example of just such discoloration / weathering in the ridge that leads into an alluvial fan on this link here[/u]
The two ridges you see were a 'mountain' pre 1995 which collapsed. The lighter material in the centre of the two ridges is lighter - less weathering and the spillage continues into the alluvial fan.

Jim correct me please if I'm wrong. I'm certainly NOT a geologist - just an interested lay person
 

Offline JimBob

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« Reply #11 on: 05/11/2007 16:53:37 »
Alas, Alandriel, no. This is not the same sort of phenomena. This is a startling example of a mountain cut in two by faulting - a volcano that has a fault running under it - but the difference in color is just shadows.

(It's the old light and mirror trick you tried to pull - think I am stupid????)
 

Offline Yousaf

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earthquake
« Reply #12 on: 05/11/2007 21:06:11 »
JimBob Thanks for convincing reply...but some people says its heppens becasuse of under ground nuclear test, like when pakistani (on 28 May 1998) nuclear tests occurred at the Chagai Hills, and same thing happend
here Satellite Images of Pakistan's Nuclear Test Sites
newbielink:http://www.isis-online.org/publications/southasia/satindex.html [nonactive]
front view
cns.miis.edu/research/india/img_cha1.htm


Yousaf,

Thank you for joining and asking this question. Welcome!

The earthquake in 2005 shook the ground so hard that rocks came apart and slid down the valley the river runs in. The white color is the color of the rock when it is freshly broken. As it sits on the ground for years and years, a process called "weathering" takes place. It causes chemical changes that make the rock get darker.

It is the same when you buy a new copper pot or tray. It is shinny and looks very nice. But if it gets broken and is thrown out it will turn green over a long time.

On Google maps, the darker the rocks you see are, the longer the surface has been stable. The whiter they get, the newer the surface.



« Last Edit: 05/11/2007 21:20:57 by Yousaf »
 

Offline JimBob

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« Reply #13 on: 06/11/2007 02:12:12 »
Yousaf,

You can tell the people who think it is because of the nuclear test is that the nuclear test caused a small earthquake at the site. It was strong enough to be measured here in the US. It was very small but was measured on the seismic recoding devices.
 

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earthquake
« Reply #13 on: 06/11/2007 02:12:12 »

 

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