THE 2002 DENALI EARTHQUAKE: INSIGHT INTO SLIP-PARTITIONING AND GROWTH OF THE ALASKA RANGE

We use SPOT image pairs to determine horizontal offsets associated with the M 7.9 November 2002 Denali earthquake in the vicinity of Slate Creek, AK. Field measurements and aerial photographs are used to further characterize the geometry of the surface rupture. The displacement field is generated using a sub-pixel cross correlation technique between SPOT images taken before and after the earthquake. The displacement field shows a signal that can be well-explained by an along-strike variation in dextral shear. We estimate a maximum of ~10 m of dextral shear in the east near 145° 30'W. Dextral slip then decreases to 4-5 m to the west near 144° 52'W. The 10 m of dextral shear measured in the vicinity of Slate Creek may be explained by fault slip being distributed over a fault zone up to several hundred meters wide. If the asymmetric slip of the November 2002 earthquake is characteristic, it implies a westward decrease in the long-term slip rate of the Denali fault. A possible mechanism to accommodate the decreasing slip rate of the Denali fault is to transfer slip to neighboring east-trending contractional structures.