Mechanisms of Postseismic and Interseismic Deformation, Southern Alaska

University Of Alaska Fairbanks Campus, Fairbanks AK

Investigators

Abstract

Freymueller 0106824 Strong postseismic deformation continues today, more than 35 years after the 1964 Alaska earthquake. The objective of this research is to understand the physical mechanisms responsible for postseismic deformation and variations in plate coupling in the 1964 earthquake rupture area. The problem of understanding postseismic deformation cannot be separated from the problem of understanding the shallow seismogenic zone; we measure the sum of the two. For the postseismic deformation, the investigators aim to determine the relative importance of creep/afterslip and viscoelastic relaxation in explaining the present and cumulative postseismic observations. Is a combination of the two classes of mechanisms required to explain the observations? If so, what is their relative importance? For variations in plate coupling, they aim to delineate as well as possible where the boundaries between strongly and weakly coupled zones lie. How sharp are these boundaries? How well do they correspond to the asperities determined from the 1964 rupture? How does the complex velocity observed in Prince William Sound relate to the transition from subduction to collision of the Yakutat block? The investigators will carry out an integrated study of GPS observations, analysis of related geodetic data including leveling and tide gauge measurements, and development of numerical models of crustal deformation applicable to both the specific tectonic environment of southern Alaska and to subduction zones in general. Continued measurements of crustal deformation in southern Alaska, combined with advanced dislocation and viscoelastic modeling, may allow the investigating team to unravel the physical mechanisms of postseismic deformation. The research will be a cooperative effort involving personnel from the Geophysical Institute, University of Alaska and the Geodynamics Branch, Laboratory for Terrestrial Physics, Goddard Space Flight Center.