The effects of segmented fault zones on earthquake rupture propagation and termination

Yihe Huang

Submitted August 2, 2017, SCEC Contribution #7386, 2017 SCEC Annual Meeting Poster #168

A fundamental question in earthquake source physics is what control the nucleation and termination of an earthquake rupture. Besides stress heterogeneities and variations in frictional properties, damaged fault zones (DFZs) that surround major strike-slip faults can contribute significantly to earthquake rupture propagation. Previous earthquake rupture simulations usually characterize DFZs as several-hundred-meter-wide layers with lower seismic velocities than host rocks, and find earthquake ruptures in DFZs can exhibit slip pulses and oscillating rupture speeds that ultimately enhance high-frequency ground motions. However, real DFZs are more complex than the uniform low-velocity structures, and show along-strike variations of damages that may be correlated with historical earthquake ruptures. These segmented structures may either prohibit or assist rupture propagation and significantly affect the final sizes of earthquakes.

To better understand earthquake rupture in segmented fault zones, we will present dynamic rupture simulations with segmented fault zones. We will show whether an earthquake rupture can reach the intact rock outside the DFZ depend on the rupture propagation distance in the DFZ, the nucleation size of the earthquake, the DFZ widths, and the DFZ sharpness. We find an earthquake nucleated in the DFZ with its nucleation size below the critical value of the intact rock can break through the DFZ if its rupture distance in the DFZ is sufficiently long. In other words, an earthquake nucleated in the DFZ can terminate when it reaches the intact rock if its rupture distance in the DFZ is relatively short. Our results suggest that a priori knowledge of properties of segmented fault zones is of great importance for predicting sizes of future large earthquakes on major faults.

Citation
Huang, Y. (2017, 08). The effects of segmented fault zones on earthquake rupture propagation and termination. Poster Presentation at 2017 SCEC Annual Meeting.


Related Projects & Working Groups
Fault and Rupture Mechanics (FARM)