GeologyRocksA Question on Faults
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As a sedimentologist, I'm in
Fri, 07/25/2008 - 09:44As a sedimentologist, I'm in no way qualified to to answer your question, but I'm going to anyway 
Fault's can "move" in some sense, as such as their centre of movement can migrate over time, meaning old faults become abandoned. However, once a fault, always a fault and that weakness in the rock will remain there until it is eroded away one way or another.
However, faults in the crust stay with the plate they are on - they don't stay still with reference to absolute co-ordinates, but they do stay put with reference to the plate co-ordinates. So in that sense, the faults do move like the plates.
Some faults have endured for eons - take the 4 main faults in Scotland: Moin thrust, Great Glen, Highland Boundary and Southern Upland. Still with us today and 100's of millions of years old. Some old faults are get "reactivated" during later tectonics events. Classic examples are the Carboniferous-Permian faults from the Variscan Orogeny which were normal faults, were re-used as compressional faults in the Cretaceous during the Alpine Orogeny. These are very visible on seismic sections of the North Sea.
Hope this helps and isn't too confusing!
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A Question on Faults
Submitted by Rock Fly on Thu, 07/24/2008 - 21:39.I wondered if anyone out there knows whether or not faults can move? I understand that continenal plates are in constant motion due to convection in the mantle, and I know small faults can open up in ocean lithosphere, but do these same rules apply to the much larger faults at the edge of continental margins?
Do these marginal faults endure over eons, do they also slowly move across the surface of the Earth in much the same way as the plates move?
I'm not sure?!