1. Campbell & Bozorgnia NGA Ground-Motion Relation
NGA Workshop #8
April 12, 2005

2. Introduction Used latest flatfile dated March 21, 2005
Extended distances from 60 to 200 km
Excluded aftershocks
Excluded poorly recorded events
Aspect ratio (AR) not explicitly modeled
Model captures observed trend with AR
Used two-step nonlinear regression

3. Modeling and Results Magnitude scaling decreases for M > 6.5
No over-saturation with magnitude is required
Attenuation decreases with magnitude
Buried reverse faults have high amplitudes
Reverse-faulting factor increases with dip
Normal-faulting somewhat lower than SS
Nonlinear soil term from simulations
Sigma nearly constant with magnitude