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Aseismic Deformation in Subduction Megathrusts: Central Andes and North-East Japan


Ortega Culaciati, Francisco Hernan (2013) Aseismic Deformation in Subduction Megathrusts: Central Andes and North-East Japan. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/BHDB-KH07.


We aim to characterize fault slip behavior during all stages of the seismic cycle in subduction megathrust environments with the eventual goal of understanding temporal and spatial variations of fault zone rheology, and to infer possible causal relationships between inter-, co- and post-seismic slip, as well as implications for earthquake and tsunami hazard. In particular we focus on analyzing aseismic deformation occurring during inter-seismic and post-seismic periods of the seismic cycle. We approach the problem using both Bayesian and optimization techniques. The Bayesian approach allows us to completely characterize the model parameter space by searching a posteriori estimates of the range of allowable models, to easily implement any kind of physically plausible a priori information and to perform the inversion without regularization other than that imposed by the parameterization of the model. However, the Bayesian approach computational expensive and not currently viable for quick response scenarios. Therefore, we also pursue improvements in the optimization inference scheme. We present a novel, robust and yet simple regularization technique that allows us to infer robust and somewhat more detailed models of slip on faults. We apply such methodologies, using simple quasi-static elastic models, to perform studies of inter- seismic deformation in the Central Andes subduction zone, and post-seismic deformation induced by the occurrence of the 2011 Mw 9.0 Tohoku-Oki earthquake in Japan. For the Central Andes, we present estimates of apparent coupling probability of the subduction interface and analyze its relationship to past earthquakes in the region. For Japan, we infer high spatial variability in material properties of the megathrust offshore Tohoku. We discuss the potential for a large earthquake just south of the Tohoku-Oki earthquake where our inferences suggest dominantly aseismic behavior.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Aseismic deformation, subduction, megathrust, inverse theory, Tohoku, earthquake, central Andes, Japan, GPS
Degree Grantor:California Institute of Technology
Division:Geological and Planetary Sciences
Major Option:Geophysics
Minor Option:Computational Science and Engineering
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Simons, Mark
Thesis Committee:
  • Clayton, Robert W. (chair)
  • Simons, Mark
  • Ampuero, Jean-Paul
  • Avouac, Jean-Philippe
Defense Date:28 May 2013
Non-Caltech Author Email:ortega.caltech (AT)
Record Number:CaltechTHESIS:06102013-122003618
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:7884
Deposited By: Francisco Hernan Ortega Culaciati
Deposited On:17 Jun 2013 22:07
Last Modified:04 Oct 2019 00:02

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