[Rockhounds] New Madrid fault

[Mr EMan]

Coming late to the well posted thread... Historically an absence of movement was an indicator of an overdue rupture not an exhaustion of potential. I guess the short answer in this research concludes that the stretched zone from the NMFzone is now in equilibrium.  

As to the original question, traces of the fault are at ground level but the bedrock is covered by river and glacial sediments.  I don't recall what the oldest sand blowout to be dated, but I do know that several have been excavated from the 1811 quake and there are some older ones.

 The failed rift of the New Madrid was believed started sometime after the Triassic(190mya) and I've been told by a researcher that there was evidence of a mantle plume forming there. Unlike Hawaii it was mid-sized and traveled under the eastern US(technically the NA Plate moved westward) and the remnant of that mantle plume is the Bermudas.  For what it is worth.

Eman


--- On Sat, 3/21/09, J Bryan Kramer <codeburner at gmail.com> wrote:

> I thought some may be interested in this:
> 
> <http://www.sciencedaily.com/releases/2009/03/090313145956.htm>
 
> Do deep subsurface faults always produce measurable surface
> movement?