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GPS Used To Monitor Continental Drift
metz2000 writes "BBC News is reporting that a team of scientists from Nottingham (UK) are using GPS to measure sea levels and continental drift. The team has around 50 stations across the UK, and use GPS technology to track miniscule changes in altitude and location. This allows the team to gain an understanding of how the UK landmass is likely to change over the coming centuries. They have discovered that the British Isles are tilting, with the north of the country gaining altitude and the south of the country 'sinking'."
well this should sort the north/south divide and tilt (apollogies for pun) the house price difference to the north.....
just my 2 (euro) cents worth
Alex
Considering a lot of GPS receivers have an error of + or - 10 feet or so, I wonder if they are using very precise equipment, or if having the redundancy of many units makes up for the rough estimates GPS satelites give.
http://almostsmart.com
...you tell me this *after* I've just bought a house in Southampton. Bummer. I knew the must be *one* good reason to live in Scotland...
Nick...
I didn't realize that GPS was accurate enough for that...
I think i heard once that there were two types of recievers, one was more error prone, but gave you an updated location every second, the second was very, very accurate, but took over 10 minutes to get a position fix.
can anyone clue me in here?
I think you can extrapolate this data into a correlation with population. Look at the warnings from the 1970s about halting population growth in California, especially west of the San Andreas Faultline. There were no changes, and then an earthquake strikes.
Now the most populated area of the UK is sinking and the rest rising. If you think about it, it is quite logical. The weight of london alone is billions upon billions of tonnes, the building and auto infrastructure, not to mention several million people.
We are having a much greater effect on the planet than anyone could know.
RST
Lifing at one and and sinking at the other? Where have I heard this before?
Oh yeah, that's right... the Titanic...
Sounds to me like this tilting is just the land settling down after the last ice age. The north of the country used to be covered in ice, while the south was clear. Now that the weight of the ice has gone, the land is just seeking a point of equilibrium.
The fact that the northern part of Europe is rising and the southern part is sinking (for a rather broad definition of southern: Holland is sinking too), has been known for a long time. I was told in highschool (think before 1983) that this is due do the northern part having been pushed downwards during ice age(s) due to the massive weight ot the ice. When the ice last retreated, the current tilting movement was initiated.
Linux user since early January 1992.
Slightly OT, but just to mention that imaging microwave radar (as those mounted in the ENVISAT or ERS satellites, for example) is also being used to monitor small changes in elevation, using a technique based on interferometric SAR (which is behind the Shuttle Radar Topography Mission.
The benefit of using a satellite orbiting around the Earth is that you don't need to deploy all the "base stations". If you want to find out more, google for "differential interferometry" or somesuch :-)
And if they relocate people to the north, will it stop the process?
..in how they use GPS to make such precise measurements you can read about it here:
Using GPS to Separate Crustal Movements and Sea Level Changes at Tide Gauges in the UK
Application of the Dual-GPS Concept to Monitoring Vertical Land Movements at Tide Gauges
Whenever the offence inspires less horror than the punishment, the rigour of penal law is obliged to give way...
From "Navigation Satellites & GPS v2.2.3 / 01 dec 02 / gvgoebel@earthlink.net /"
Geophysicists have been exploiting GPS since the mid-1980s, using it to measure continental drift and the movement of the Earth's surface in geologically active regions. They have been able to obtain accurate surface measurements to within a few millimeters through a procedure known as "carrier tracking", which is even more accurate than differential GPS. Carrier tracking actually senses the phase of the carrier signals on which the location code sequences are broadcast. It is, not surprisingly, a tricky and subtle procedure, and not applicable for general use.
On the contrary, while the receivers that you spend a hundred bucks on are indeed not accurate enough, GPS based geodesy is a raging success. They use very expensive receivers with multiple frequencies and occupy sites for hours at a time to get the kinds of numbers needed for geodetic measurements. Been going on for years. The major inaccuracies have to do with index-of-refraction effects in the atmosphere (hence the need for multi-frequency instruments).
.. I thought it couldn't sink any further. :)
I always new there was something fishy in the south side of britain. Ah well.. atleast now they have showed that it will hit rock bottom soon
Whats the point of having excellent karma if not to spend it every once in a while?
"They have discovered that the British Isles are tilting, with the north of the country gaining altitude and the south of the country 'sinking'"
GREAT DISCOVERY *sarcasm*
Since the late pleistocene the big icesheets on top of Northern Europe disappeared by global climat change from glacial to interglacial (cfr. Iversen model). As a concequence of this loss of mass on top of these plates they began to bounce back up. Imagine taking a piece of drifting wood, push it down. If you lift your finger it will rise up again. The same principal goes for continental plates and is called isostatic uplift.
So, since the beginning of the holocene and end of the pleistocene countries now known as Sweden, Norway began to rise and Belgium and the Netherlands for example began to sink, because the y once were uplifted by the weight on the northern part of europe.
It seems normal that these consequences aren't just limited to european main land but also influence the UK. In fact Scotland has had a big icecap during the last iceage so the isostatic uplift of Scotland and the drowning, if you may call it that, of the south of the UK isn't exactly new.
They may claim having measured it, but they certainly may not claim the discovery of these changes because that's veeeeeery old news.
GPS accuracy is somewhat consistent among manufacturers, and is generally more accurate the more you pay for the equipment. However, there is always a margin for error. For example, Wilson's GPS Accuracy page states that vertical accuracy depends on "latitude (errors for vertical accuracy rapidly increase with latitudes greater than 65 degrees), receiver/antenna, local geometry/multipath and satellite geometry (VDOP)"
The real question is are the Nottingham group using high grade and control tested equipment and have they properly accounted for discrepency. Stating that Scotland is rising two millimeters a year is quite the claim.
I'm wrong and so are you.
..some scientists studying the "sinking" effect have noted CowboyNeal's recent move to Southampton.
My journal has hot
A lot of bodies of water are above sea level. The Colorado river starts at 9,010 feet above sea level.
From the article:
GPS measurements have also allowed scientists to show that the UK is drifting about 2-3 cm each year in a north-easterly direction.
All I want is a secure system where it's easy to do anything I want. Is that too much to ask ~~ Randall Munroe
The tilt, at least, has been known for a quite a while; I remember joking with a friend from London that London might be horrible, but if we just waited a few million years the problem would be solved (we were in Scotland). That was back in the late eighties.
This link has the best introduction to mapping and GPS I have ever read.
All I want is a secure system where it's easy to do anything I want. Is that too much to ask ~~ Randall Munroe
This is hardly news, I was taught about this 10 years ago at school.
GPS measurements have also allowed scientists to show that the UK is drifting about 2-3 cm each year in a north-easterly direction.
I disagree. The UK is only drifting north. Since we have no east or west pole, the east-west component of the velocity can only be stated relative to some other plate. We could just as well assert that the UK is stationary in the east-west direction, and the other plate is moving west.
This was already common enough knowledge for those interested in the subject ... the south east & east anglia are sinking, the north west rising.
The sky is falling! The sky is falling!!!
:)
Oh--wait--the ground is rising...
umm--nevermind
This seems like very old news to me.
I seem to recall being told this in the early 1980s at school.
Apperently it's the "rebound" effect. In the last ice age all the ice caused Scotland and Northern England to sink under it's weight.
Since it all melted it's been slowly rising.
I can't remember why southern England is sinking though. Maybe there's a pivet somewhere through Shefield or something ?
I remember an in-depth discussion of the tilting effect on the Open University in the late '80s.
Geologists have been measuring micro-motions of the earth since GPS started in the early 1990s. There are thousands of talks on the subject here .
"Continental drift occurs on the order of feet per eon."
Actually, rates range up to 20 cm/year in some places. In this case, I thing they were saying 2-3 cm/yr. This is very measureable by continuous GPS from permanent stations; see a lot of these other comments for why.
These GPS networks have been used with great success over the past 15 years or so in places like Japan, California, and New Zealand, to name a few. Nice to see it getting put in in other places
They have discovered that the British Isles are tilting, with the north of the country gaining altitude and the south of the country 'sinking'
That explains the difference in house prices up North and down South. I wonder when they'll start advertising southern homes as "temporary accomodation"? :o)
Resistance is futile. Reactance buggers it up.
I thought I would include some links to similar projects:
SCIGN -- Southern California Integrated GPS Network
http://www.scign.org/
This GPS array has 250 active stations throughout SoCal continuously monitoring crustal deformation. SCIGN was started after the 1994 Northridge Earthquake and has helped the determination of the velocity field in Southern California produced by SCEC.
An interactive map of station locations can be found at:
http://pasadena.wr.usgs.gov/scign/Analysis/
SCEC -- Southern California Earthquake Center
http://www.scec.org
This is the umbrella organization for EQ research in Southern California and is the parent organization of SCIGN.
PBO/Earthscope -- Plate Boundary Observatory
http://www.unavco.org
One of the most exciting new developments in GPS. Recently the US Congress approved the Earthscope initiative which includes 3 separate parts. The GPS portion is the PBO which will include 875 new stations from the Mexican border through Washington and Alaska. This massive array will be built over the next 5 years.
There are also several other regional deformation arrays include the Basin Range network, The Bary Area network, and a cluster of sites around Parkfield, CA.
Equipment:
The GPS equipment used at these sites are commercially available dual frequency geodetic quality receivers which can recover the military code without needing the military keys. The receivers are capable of good precision when operated alone and are capable of sub-millimeter precision when used in a continuously operating network.
This type of processing requires extremely accurate satellite orbits provided by the International GPS Service (http://igscb.jpl.nasa.gov/).
These large GPS arrays have been deployed throughout the world where there is a seismic hazard. Japan is one of the predominant countries with large GPS networks in place.
We encourage you to look at the various websites and learn about these projects and the science that they produce.
--Keith
SCIGN Network Coordinator