EGU22-4536
https://doi.org/10.5194/egusphere-egu22-4536
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Transient rheology of the continental crust

Sagar Masuti1, Jun Muto2, and Erik Rybacki1
Sagar Masuti et al.
  • 1GFZ German Research Centre For Geosciences, Germany (sagar.masuti@gmail.com)
  • 2Tohoku University, Sendai, Japan.

Postseismic relaxation after large earthquakes induces transient deformation of the solid Earth, particularly in the deeper part of the crust. The deformation of the upper and lower crust are mainly controlled by the rheological behavior of quartz and feldspar, respectively. The mechanical properties of quartz and feldspar at steady-state creep conditions are well constrained and flow law parameters are known from experimental calibrations. However, the physical mechanism underlying transient creep is poorly understood and the corresponding flow law parameters are unknown so far. Here, we constrain a constitutive framework that captures transient creep and steady state creep consistently using the mechanical data from laboratory experiments. The constitutive framework represents a Burgers assembly with a thermally activated nonlinear stress versus strain-rate relationship for the dashpots. Using the Markov chain Monte Carlo (MCMC) method, we uniquely determine the flow law parameters for both quartz and feldspar. We find an activation energy of 70±20 kJ/mol and a stress exponent of 2.0±0.1 for transient creep of quartz. For feldspar, the best-fit activation energies are 280±30 and 220±20 kJ/mol with stress exponents of 1.0±0.2 and 0.9±0.1 under mid- and high-temperature conditions, respectively. The stress exponents and activation energies of transient creep are consistently smaller than those of steady-state creep for both quartz and feldspar. The flow law parameters determined in this study could be used to quantify the contribution of transient creep in the postseismic deformation following a large continental earthquake. 

How to cite: Masuti, S., Muto, J., and Rybacki, E.: Transient rheology of the continental crust, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4536, https://doi.org/10.5194/egusphere-egu22-4536, 2022.