Please note that this session was withdrawn and is no longer available in the respective programme. This withdrawal might have been the result of a merge with another session.

From mylonite to Maxwell: reconciling rheologies from geodetic, geological and experimental observations of post-seismic deformation
Co-organized by
Convener: Camilla PenneyECSECS | Co-conveners: Adriano GualandiECSECS, Alissa Kotowski, Chris RollinsECSECS

Earthquakes induce stress changes that drive accelerated frictional creep (afterslip) and viscoelastic deformation in the ductile lithosphere and asthenosphere. Post-seismic geodetic data often show multiple relaxation timescales, with both transient and long-term effective viscosities invoked to explain the observations. Similarly, models of frictional behaviour may require different short- and long-term fault slip rates. How the multiple timescales in these first-order physical models relate to, and result from, potentially complex, heterogeneous geology is an open question. Moreover, geodetically inferred rheologies and frictional models characterize relatively short time scales and it is important to understand how they relate to geological deformation on broader temporal and spatial scales. Whilst models of post-seismic deformation are typically laterally homogeneous with limited vertical heterogeneity, geological and experimental studies demonstrate 1) viscosity’s inverse-exponential dependence on temperature, 2) localisation of deformation within shear zones, and 3) localised transient rheologies comprising synchronous brittle and ductile deformation.

What can geodetic observations and simple models of post-seismic deformation tell us about the geological complexity of the lithosphere and asthenosphere? And what constraints can geological and experimental data place on physical models? We welcome studies based on-, or combining field observations, geodetic measurements, rock mechanics, numerical modelling, theory or other approaches aimed at explaining post-seismic displacement observations, and, more broadly, at reconciling estimates of lithospheric and asthenospheric rheology across multiple timescales.