Nonlinear Behavior of Strong Surface Waves Trapped in Sedimentary Basins

Norman H. Sleep

Published 2010, SCEC Contribution #1327

Numerical calculations and observations indicate that surface waves reverberate within sedimentary basins. A site response approach is inapplicable to the nonlinear attenuation of these waves as the energy passes repeatedly through the shallow subsurface. Computed dynamic stresses obtained by using published ShakeOut calculations (Graves et al., 2008) indicate that nonlinear attenuation is modest but not negligible in the Los Angeles, California, basin for large earthquakes on the San Andreas fault. The dominant surface waves have velocity amplitudes of ∼1:5 m sec-1 and periods ∼3:5 sec. Around 20% of the total elastic strain energy resides above dynamic/lithostatic stress ratios of 0.2 for both Rayleigh and Love waves where prestressed rock is highly to fail somewhat in friction.

Citation
Sleep, N. H. (2010). Nonlinear Behavior of Strong Surface Waves Trapped in Sedimentary Basins. Bulletin of the Seismological Society of America, 100(2), 826-832. doi: 10.1785/0120090150.