GS24b and GS24bc Ground Motion Models for Active Crustal Regions Based on Non-Traditional Modeling Approach

An expanded Pacific Earthquake Engineering Research (PEER) Center Next Generation Attenuation Phase 2 (NGA-West2) ground motion database compiled from shallow crustal earthquakes in active crustal regions (ACR) is used to develop closed form GS24b backbone ground motion model (GMM) for the “average” RotD50 horizontal components of peak ground acceleration (PGA), peak ground velocity (PGV) and 5% damped elastic pseudo-absolute response spectral accelerations (SA). GS24b model is applicable to earthquakes with moment magnitudes 4.0 ≤ M ≤ 8.5, at rupture distances of 0 ≤ Rrup ≤ 400 km, with time-averaged S-wave velocity in the upper 30 m of the profile 150 ≤ VS30 ≤1500 m/s, and for periods 0.01 ≤ T ≤10 s. The new backbone model includes VS30 site correction developed based on multiple representative S-wave velocity profiles. For crustal waves attenuation we are using apparent anelastic attenuation of SA -- QSA (f, M). In contrast to the GK17 the GS24b backbone is a generic ACR model designed specifically to be adjusted to any ACRs. The GS24bc is an example of a partially non-ergodic model created by adjusting the backbone GS24b model for magnitude M, S-wave velocity VS30 and fault rupture distance Rrup residuals.