Physics of dynamic rupture pulses and macroscopic earthquake source properties in elastic and plastic media

This dissertation concerns complexities in earthquake source dynamics and the resulting implications for seismic ground motion. Its findings base on numerical and analytical investigations that are validated by comparison with seismic observations. The core of this work is a comprehensive set of 2D in-plane dynamic rupture simulations with a spectral element method incorporating faults. The fault rheology is governed by a velocity-andstate-dependent friction law, utilising severe velocity-weakening at high slip rates and a homogeneous initial stress state. Motivated by seismological observations, laboratory experiments, and theoretical models which indicate that earthquakes can operate in different manners, we classify a diversity of rupture styles based on their stability (decaying, steady, or growing), rupture speed (subshear or supershear), healing properties (cracks or pulses), and complexity (simple or multiple fronts). Such rupture styles and their transitions depend on the state of stress and on the strength of the fault, and thus may help identify rheological parameters along active fault zones. We study the alteration of macroscopic rupture properties by off-fault energy dissipation into plastic deformation, which may be triggered by high stress concentrations at earthquake rupture fronts. Investigating in detail the energy balance and equation of motion of self-similar pulse-like ruptures, we are able to define quantitative relations between off-fault energy dissipation and macroscopic source properties. These findings contribute to a self-consistent theoretical framework for the study of the earthquake energy balance based on observable earthquake source parameters. The emanated seismic wave fields contain signatures of rupture styles and plasticity in near-field seismograms, source spectra, and in damage patterns off the fault. The asymmetrically induced plastic strain fields contribute to the total seismic moment. Identifying the diversity of rupture patterns in real earthquakes poses an interesting observational challenge. The long-term objective of this work is to provide physical constraints with respect to the source of earthquakes applicable in strong ground motion prediction, seismic hazard analysis, and source inversion methods.

@phdthesis{id1844,
  author = {Gabriel, Alice-Agnes},
  language = {en},
  note = {A dissertation submitted to ETH Zurich for the degree of Doctor of Sciences},
  type = {Diss. ETH No. 20567},
  school = {ETH Zurich},
  title = {Physics of dynamic rupture pulses and macroscopic earthquake source properties in elastic and plastic media},
  url = {http://dx.doi.org/10.3929/ethz-a-009761502},
  year = {2013},
}

%O Thesis
%A Gabriel, Alice-Agnes
%G en
%O A dissertation submitted to ETH Zurich for the degree of Doctor of Sciences
%9 Diss. ETH No. 20567
%C ETH Zurich
%T Physics of dynamic rupture pulses and macroscopic earthquake source properties in elastic and plastic media
%U http://dx.doi.org/10.3929/ethz-a-009761502
%D 2013