SCEC Award Number 17144 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title Investigating seismic cycles with thermal pressurization using physical models and numerical simulations
Investigator(s)
Name Organization
Paul Segall Stanford University Camilla Cattania Stanford University
Other Participants
SCEC Priorities 3f, 2c, 3c SCEC Groups FARM, SDOT, EFP
Report Due Date 06/15/2018 Date Report Submitted 02/04/2019
Project Abstract
 The project aims to better understand features of seismicity with a combination of 2-D numerical simulations and fracture mechanics based models. Simulations in two dimensions indicate that the dimension of the velocity weakening region $W$ controls important features of seismic cycles, such as: 1) the occurrence and number of partial ruptures; 2) temporal clustering vs. periodicity; 3) the frequency-size distribution. Understanding these regimes is the starting point for modeling seismic cycles. Simple crack models predict that number of partial ruptures scales that $\sqrt{W/L_{\infty}}$, where $L_{\infty}$ is the nucleation dimension; this result is supported by simulations over a wide range of parameters. For sufficiently large $W/L_{\infty}$ (few hundreds) Omori-type temporal clustering occurs, due to fast reloading by afterslip. In this regime we also find a power-law distribution of rupture lengths.
Intellectual Merit This work develops simple fracture mechanics models to understand the frequency-magnitude distribution and temporal clustering of earthquakes on uniform planar faults loaded by adjacent creep. We demonstrate that even very simple faults (homogeneous, planar and isolated faults in an elastic medium) can produce a wide range of earthquake magnitudes, if they are sufficiently large compared to the nucleation dimension.
Broader Impacts This project supported the intellectual development of an international Postdoctoral student.
Exemplary Figure Figure 4. Distribution of rupture lengths for simulations with a=b = 0.75. Figure shows that as the size of the velocity weakening region increases the size distribution of simulated ruptures becomes power law, even though there is neither geometric or material heterogeneity in the model. (Camilla Cattania)