Seismicity and Active Tectonics of Interior Alaska

• Main Author: Evelyn Price
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Figure 1. Continental Alaska. Circles are at the; Andreas; Pacific; alaska range; Alaska
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.577.8544; http://www.scec.org/instanet/01news/es_abstracts/Price_alaska.pdf

Deformation of Earth’s continental crust at actively deforming plate boundaries around the world is often distributed across a zone whose width can range from hundreds to thousands of kilometers. This is true of the Western United States where major plate boundary strain is concentrated in California and partitioned between the San Andreas Fault (SAF) and the Eastern California Shear Zone (ECSZ). The ECSZ, in particular, has been the region where California’s largest earthquakes of the past 10 years have occurred. The detailed study of the hazardous plate boundary in California has led to many important insights into mechanical interactions among Earth’s deforming crust, its faults on which tectonic stresses are concentrated, and the underlying mantle. Each deforming geologic system, while complex unto itself, can be considered only a single sample within a continuum of how the crust could deform given a range of rheologies, boundary conditions, and applied stresses. We are fortunate to have at least two samples of distributed continental plate boundary deformation with clearly-defined regions of strain partitioning in the United States: the Western US and southern to interior Alaska. In Alaska, plate boundary strain is spread over a width of 300 km (Figure 1) and is partitioned into regions defined by the direct subduction of the Pacific Plate, the uplift of the Alaska range, strike-slip faulting on the Denali fault, and finally shearing and block rotation within Alaska’s interior. Like the ECSZ, interior Alaska’s shear zone is capable of producing hazardous magnitude 7 earthquakes (three historic ones are recorded) and may accommodate a significant portion of plate boundary strain.