3D Ground-Motion Simulations of M-w 7 Earthquakes on the Salt Lake City Segment of the Wasatch Fault Zone: Variability of Long-Period (T >= 1 s) Ground Motions and Sensitivity to Kinematic Rupture Parameters
Por:
Moschetti, Morgan P., Hartzell, Stephen, Ramirez-Guzman, Leonardo, Frankel, Arthur D., Angster, Stephen J., Stephenson, William J.
Publicada:
1 ago 2017
Resumen:
We examine the variability of long-period (T >= 1 s) earthquake ground
motions from 3D simulations of M-w 7 earthquakes on the Salt Lake City
segment of the Wasatch fault zone, Utah, from a set of 96 rupture models
with varying slip distributions, rupture speeds, slip velocities, and
hypocenter locations. Earthquake ruptures were prescribed on a 3D fault
representation that satisfies geologic constraints and maintained
distinct strands for the Warm Springs and for the East Bench and
Cottonwood faults. Response spectral accelerations (SA; 1.5-10 s; 5%
damping) were measured, and average distance scaling was well fit by a
simple functional form that depends on the near-source intensity level
SA(0) (T) and a corner distance R-c: SA (R,T) = SA(0) (T) (1 +
(R/R-c))(-1). Period-dependent hanging-wall effects manifested and
increased the ground motions by factors of about 2-3, though the effects
appeared partially attributable to differences in shallow site response
for sites on the hanging wall and footwall of the fault. Comparisons
with modern ground-motion prediction equations (GMPEs) found that the
simulated ground motions were generally consistent, except within deep
sedimentary basins, where simulated ground motions were greatly
underpredicted. Ground-motion variability exhibited strong lateral
variations and, at some sites, exceeded the ground-motion variability
indicated by GMPEs. The effects on the ground motions of changing the
values of the five kinematic rupture parameters can largely be explained
by three predominant factors: distance to high-slip subevents, dynamic
stress drop, and changes in the contributions from directivity. These
results emphasize the need for further characterization of the
underlying distributions and covariances of the kinematic rupture
parameters used in 3D ground-motion simulations employed in
probabilistic seismic-hazard analyses.
Filiaciones:
Moschetti, Morgan P.:
US Geol Survey, POB 25046,MS 966, Denver, CO 80225 USA
Hartzell, Stephen:
US Geol Survey, POB 25046,MS 966, Denver, CO 80225 USA
Ramirez-Guzman, Leonardo:
Univ Nacl Autonoma Mexico, Coordinac Ingn Sismol, Inst Ingn, Univ 3000, Mexico City 04510, DF, Mexico
Frankel, Arthur D.:
Univ Washington, US Geol Survey, Box 351310, Seattle, WA 98195 USA
Angster, Stephen J.:
Univ Reno, Dept Geol Sci, Reno, NV USA
US Geol Survey, POB 25046,MS 966, Denver, CO 80225 USA
Stephenson, William J.:
US Geol Survey, POB 25046,MS 966, Denver, CO 80225 USA
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