A linear viscoelasticity for decadal to centennial time scale mantle deformation

Area of Science:

• Geophysics
• Solid Earth Science
• Rheology

Background:

• The extended Burgers material (EBM) model is a linear viscoelastic theory used in geophysics.
• It is important for parameterizing laboratory data, interpreting seismic wave velocity and attenuation, and analyzing planetary tidal dispersion and quality factor Q.
• The model assumes a distribution of relaxation spectra linked to rock grain boundary and interior granular mobility, with Maxwellian long-term behavior.

Purpose of the Study:

• To isolate parameters of the EBM that are applicable to post-seismic relaxation processes in the upper mantle and tidal studies.
• To investigate the influence of EBM transient rheology on geodetic interpretations of crustal motions induced by unloading.

Main Methods:

• Utilized the linear theory of viscoelasticity to isolate EBM parameters.
• Applied analytical Laplace transformed solutions of Boussinesq's half-space load problem.

Main Results:

• Identified EBM parameters relevant to post-seismic relaxation and tidal studies.
• Demonstrated that EBM transient rheology significantly impacts geodetic interpretations of unloading-induced crustal motions, even on sub-decadal timescales.

Conclusions:

• The isolated EBM parameters are applicable to post-seismic relaxation, tidal studies, and glacial isostatic adjustment.
• EBM provides a robust framework for understanding complex rock deformation phenomena across various geophysical applications.