ShallowS‐Wave Well Logs as an Indicator of Past Strong Shaking from Earthquakes on the Newport–Inglewood Fault
Norman H. SleepPublished September 8, 2015, SCEC Contribution #6014
Numerical calculations assuming linear elasticity by Böse et al. (2014)
indicate that an Mw 7.75 earthquake on the Newport–Inglewood fault would cause
5 m/s of horizontal peak ground velocity (PGV) within the Los Angeles basin. However,
the dynamic strain from this event would take much of the uppermost few hundred
meters of basin rock beyond its frictional elastic limit. Stiff quartz-rich beds within the
basin are fragile geological features that would fail and crack before the rest of the clayrich
rock mass. Repeated cracking would reduce the shear modulus of the quartz-rich
beds to the level that cracking barely occurred during strong events. When interpreted in
this way, data from such stiff beds near the Los Angeles International Airport indicate
past PGV of ∼1.6 m/s, comparable with near-field records from the strike-slip 2002
Denali and 1992 Landers earthquakes. Numerical calculations capable of representing
nonlinear failure within shallow bedded rocks are warranted.
Citation
Sleep, N. H. (2015). ShallowS‐Wave Well Logs as an Indicator of Past Strong Shaking from Earthquakes on the Newport–Inglewood Fault. Bulletin of the Seismological Society of America,. doi: 10.1785/0120150026.
Related Projects & Working Groups
SOSAFE, Strong ground motions
