HR: 1320h
AN: S43A-0987    [Abstracts]
TI: Liquefaction of Sensitive Soils during Earthquakes
AU: * Wang, C
EM: chiyuen@seismo.berkeley.edu
AF: Department of Earth and Planetary Science, University of California, Berkeley, CA 94720
AU: Dreger, D S
EM: dreger@seismo.berkeley.edu
AF: Department of Earth and Planetary Science, University of California, Berkeley, CA 94720
AB: The occurrence of liquefaction during earthquakes of a given magnitude (M) is confined within a particular distance from the earthquake source, i.e., the liquefaction limit (Rmax). We interpreted Rmax as the distance at which the energy of the seismic waves has decayed to a threshold energy required for saturated soils to liquefy, beyond which the seismic energy is too weak to cause further liquefaction. Combining an empirical relation between M and Rmax with Bath's relation between M and earthquake energy (Es) we obtain an empirical relation between Es and Rmax. The relation implies a threshold energy of 0.032 J/m3 for liquefaction and a very small effective quality factor Q. The threshold energy, when interpreted in the light of a threshold shear amplitude for liquefaction, implies an effective shear modulus ~ 0.1 - 10 MPa, which is two orders of magnitude or more smaller than the elastic shear moduli for alluvial sands estimated from shear wave velocity. The atypical shear modulus and Q show that liquefaction of sensitive soils during earthquakes may be preceded by nonlinear behaviors, with drastic degradation of shear rigidity and severe dissipation of seismic energy.
DE: 7223 Seismic hazard assessment and prediction
DE: 5114 Permeability and porosity
DE: 5470 Surface materials and properties
DE: 7212 Earthquake ground motions and engineering
SC: Seismology [S]
MN: 2004 AGU Fall Meeting