Northridge 1D rock/soilSimulation (36 sites)

Loma Prieta 1D east/west SAFSimulation (56 sites)

Kinematic representation of heterogeneous rupture on a finite fault.

- slip amplitude - slip direction (rake) - rupture velocity - rise time

Wave propagation modeled using full waveform Green’s functions calculated for 1D or 3D velocity structure.

Site response based on Vs30 using

Borcherdt’s (1994) short- and mid-period amplification factors.

Deterministic Methodology (f < 1 Hz) Stochastic Methodology (f > 1 Hz)

Limited kinematic representation of heterogeneous rupture on a finite fault (extension of Boore, 1983).

- slip amplitude (stress parameter = 50)

- rupture velocity - rupture duration - average radiation pattern - stochastic phasing

Simplified Green’s functions for 1D

velocity structure. - amplitude decays as inverse of ray

path - impedance effects based on Boore

and Joyner (1997) Site response based on Vs30 using

Borcherdt’s (1994) short- and mid-period amplification factors.

BROADBAND SIMULATION METHODOLOGY:A HYBRID DETERMINISTIC AND STOCHASTIC APPROACH

• Combine using matched filters (1 Hz) and summing in time domain

Tp Tr

A

h

Source Rupture Model

- slip distribution

- rupture timeTi = R / Vr - t (slip) Vr = 0.8 Vs

- slip velocity function

Tr = 2 x 10-9 Mo1/3

Tp = 0.2 Tr

h = 0.2 A

Site Amplification Factors (Borcherdt, 1994)

Fa = (Vref / Vsite) ma (high-frequency) Vref = Vs

30 in simulation

Fv = (Vref / Vsite) mv (mid-frequency) Vsite = Vs

30 at site

Applied in Fourier domain, although strictly defined for response spectra.

Fv

Fa

Model Bias and Standard Error: Response Spectra

Residuals vs. distance / site typeGlobal goodness-of-fit (38 sites, avg. horizontal)

Average horizontalwithout site factors

without site factors