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Constraints from GPS measurements on the dynamics of deformation in Anatolia and the Aegean
Author(s) -
England Philip,
Houseman Gregory,
Nocquet JeanMathieu
Publication year - 2016
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1002/2016jb013382
Subject(s) - lithosphere , geology , mantle (geology) , post glacial rebound , power law , geophysics , seismology , geodesy , mechanics , tectonics , physics , geomorphology , ice sheet , statistics , mathematics
Abstract We estimate the strength of the lithosphere in Anatolia and the Aegean, and the boundary forces acting upon it, using a dynamical model that treats the lithosphere as a thin fluid sheet deforming in response to variations in gravitational potential energy. This model has one free material parameter, the power law exponent, n , of the vertically averaged rheology of the lithosphere, and two parameters that specify the forces per unit length applied to its edges. Solutions to this model that best fit the velocities of 346 reliable GPS sites require an effective viscosity of the lithosphere of 10 22 to 10 21 Pa s at strain rates of 10 to 100 nanostrain per year. The best‐fitting force at the Arabia‐Anatolia boundary is consistent with the lithostatic pressure due to the high topography there, and the force at the Nubia‐Aegean boundary is consistent with the contrast in lithostatic pressure across that boundary. No additional force, from “slab rollback” or basal tractions due to convection in the mantle, is required to explain the observations. These results are supported by scaling relations derived from approximate analytical solutions. The inverse relationship between the viscosity of the lithosphere and deviatoric stress produces strong slowly deforming regions in the Southern Aegean and Central Anatolia whose motions resemble those of microplates. The distribution of geodetic strain rates within the region, and the partitioning between normal and strike‐slip faulting, are explained by the interplay between boundary conditions, internal variations in gravitational potential energy, and the power law rheology of the lithosphere.