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Alaskan Neotectonics

A compilation of 621 stress indicators in Alaska shows a fan pattern of directions radiating from the syntaxis in the St. Elias range [ Estabrook and Jacob, 1991]. In a uniform elastic material, such a stress pattern would suggest a stress singularity, or at least high values. However, a nonlinear thin-plate finite-element model with faults [ Bird, 1992b] shows that the stress magnitudes are low, and that the pattern is due to the juxtaposition of transpression on the Fairweather fault with terrane collision of the Yakutat block. Thus, Alaska is no exception to the general weakness of major faults. The same model also predicted rapid westward transport of the west Aleutian forearc, which is consistent with the evidence of seismic slip vectors [ McCaffrey, 1992].



U.S. National Report to IUGG, 1991-1994
Rev. Geophys. Vol. 33 Suppl., © 1995 American Geophysical Union