Implications of depth-dependent variations in fault zone properties for the frequency content of seismic radiation

Valere R. Lambert, & Nadia Lapusta

Submitted August 15, 2017, SCEC Contribution #7790, 2017 SCEC Annual Meeting Poster #175

Seismic observations from several recent great earthquakes - the 2004 Mw 9.2 Sumatra-Andaman, 2010 Mw 8.8 Chile, and 2011 Mw 9.0 Tohoku-Oki events – suggest that more of the high-frequency radiation from the rupture process originated from the deeper extensions of the megathrust (e.g., Meng et al., 2011; Lay et al., 2012; Yao et al., 2013). One proposed explanation is the presence of increased heterogeneity in fault frictional properties at deeper portions of the megathrust (e.g., Huang et al, 2013). We explore an alternative model in which the variation in high-frequency radiation is a natural product of depth-dependent variations in fault zone properties. In particular, increasing effective normal stress as well as associated variations in the fault zone properties such as the shear zone width and permeability, should result in depth-dependent differences in the frequency content of the resulting source-time functions at different depths. In the shallow portions of the fault, velocity-strengthening areas and partial release of slip through aseismic processes should contribute to the low high-frequency radiation from those areas. Through numerical modeling of earthquake cycles, we investigate how the expected changes in the fault zone structure and properties with depth modify the spectral distribution of the associated seismic radiation.

Citation
Lambert, V. R., & Lapusta, N. (2017, 08). Implications of depth-dependent variations in fault zone properties for the frequency content of seismic radiation. Poster Presentation at 2017 SCEC Annual Meeting.


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