Denali Fault

The Denali fault is an active intraplate dextral strike-slip fault. Notice it is not a Fitch fault as it does not follow the magmatic arc complex. Note also, that Alaska is not behaving as one rigid plate. In that the highest mountain in North America lies in proximity, the deformation complex has a major vertical component of motion, and the Denali fault is a transpressive feature. One can ask why it localized where it did? Also, the details of the mechanics of uplift are of interest. Is this a flower structure of some sort, or does some other architecture exist.

 

Tectonic setting for the Denali fault. Image taken from http://earthobservatory.nasa.gov/Study/denali/ .

USGS map of topography and earthquakes associated with Denali fault in Alaska. Taken from http://people.arsc.edu/~kcarlson/Other/EQ.html . Note the strong curvature of the topography and fault. The fault is dextral. Remember that pure strike-slip movement would follow a small circle path. If the curvature is smaller than that what are the strain implications. The topography here is driven by the deformation associated with the fault.

 

In the winter of 2002 a large (7.9) earthquake on the Denali fault produced a surface rupture, in the landscapes, glaciers included. The rupture of the snow provided a detailed, shall we3 say, striking, picture of the rupture trace. Note the fairly complex fracture geometry associated with the rupture. This is typical for strike-slip faults. Image from and a lot more information at http://ak.water.usgs.gov/glaciology/m7.9_quake/ .

This same earthquake offset the Alaska pipeline some 14 feet, which the pipeline was engineered and did accommodate. The image is from http://pubs.usgs.gov/fs/2003/fs017-03/ .

This is a USGS produced shake map, which shows the relative magnitudes of ground shaking during the 2002 earthquake. Note the elongate pattern that follows the fault. Image from http://pubs.usgs.gov/fs/2003/fs014-03/shakemap.html.

Link:

Purdue University website on GPS research on Denali.