SCEC Award Number 12122 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title Shear Localization and the Evolution of Fault Strength
Investigator(s)
Name Organization
Alan Rempel University of Oregon
Other Participants Jiangzhi Chen (PhD student)
SCEC Priorities 3e, 3d, 3b SCEC Groups FARM
Report Due Date 03/15/2013 Date Report Submitted 11/29/2015
Project Abstract
 The evolution of fault strength during earthquakes must be captured by accurate predictive models of rupture dynamics. To better understand fault-strength changes, this SCEC-funded project exam- ined: a) their implications for shear localization, b) the potential for field observations of shear-zone width to constrain the shear resistance during seismic slip, and c) strategies for parameterizing and incorporating these effects in dynamic rupture simulations. Under the PI's guidance, project gradu- ate student Jiangzhi Chen developed a new model to examine the effects of shear localization in rupture simulations. Although this effort did not proceed as initially anticipated, it eventually formed the basis for a publication by Chen and Rempel on ``Shear zone broadening controlled by thermal pressurization and poroelastic effects during model earthquakes'', Journal of Geophysical Research, 120(7) 5215--5237, 2015.
Intellectual Merit The research conducted under this grant helped to advance the SCEC4 goal of describing the evolution of fault resistance during seismic slip. By predicting shear thickness evolution, this research provides better constraints on conditions along major faults and their implications for earthquakes. A better understanding of the controls on shear-zone width may also inform the search for geological indicators of past fault behavior.
Broader Impacts This research supported a portion of the PhD research of graduate student, Jiangzhi Chen, who has since graduated and will soon begin Postdoctoral research as the next step in his STEM career.
Exemplary Figure Figure 1. Modeled evolution of (a,c) temperature and (b,d) normalized pore pressure evolution during 1 s. Figures 1a and 1b use a uniform strain rate distribution, while Figures 1c and 1d use Gaussian shearing. The pore pressure perturbation propagates faster than the temperature perturbation, since the hydraulic diffusivity is greater than the thermal diffusivity. Modified from Fig. 8 of Chen and Rempel, 2015.