Generic Ground Motion Model for Subduction Earthquakes in Japan; Implication for Cascadia Subduction Zone

Date: 4/24/2019

Time: 06:00 PM

Room: Grand Ballroom

We use the adjustable generic ground-motion model (GMM) of Hassani and Atkinson (2018) (HA18) to develop predictive relations for the amplitudes of shaking for subduction earthquakes in Japan. The database of the study is extracted from the recently developed Next Generation Attenuation for Subduction Earthquakes (NGA-Sub) database (Kishida et al., 2017). The NGA-Sub database includes ground-motion data for interface, inslab, and crustal earthquakes from subduction regions around the world, with the Japanese database contributing more than 50% of the records. The HA18 model is based on the equivalent point source approach, allowing regional modifications to its key input variables such as geometrical spreading rate, anelastic attenuation, stress parameter, near surface attenuation parameter (kappa), and crustal amplification. The GMM of this study is developed in a way to account for inferred differences in the median stress parameters and geometric spreading for interface and inslab earthquakes, and for differing attenuation in forearc and backarc regions. The GMM is developed for peak ground acceleration, peak ground velocity, and 5% damped pseudospectral acceleration (PSA) at frequencies from 0.1 to 100 Hz, for rupture distances up to 1000 km. The reference ground condition is V_S30 = 760 m/s (time-averaged shear-wave velocity in the top 30m); individual site terms relative to the model are derived for each station. In future work, the model will be adjusted for the Cascadia subduction zone to account for regional source, attenuation and site attributes that differ from those in Japan.

Presenting Author: Gail M. Atkinson

Authors