- Ground-motion model is:
where Y is in cm∕s2; α1 = -1.7918, α2 = 1.61, α3 = -1.00, α4 = -0.0058 and σ = 0.60 for CU;
α1 = 0.4089, α2 = 1.23, α3 = -1.00, α4 = -0.0016 and σ = 0.55 for SCT; α1 = 0.4656, α2 = 1.22,
α3 = -1.00, α4 = -0.0012 and σ = 0.58 for CDAO.
- Use data from 3 stations in hill (Ciudad Universitaria, CU, 22 records) and lake-bed (Secretaría de
Comunicaciones y Transportes, SCT, 15 records, and Central de Abastos, CDAO, 13 records) zones of
- Focal depths 40.0 ≤ H ≤ 128.4km.
- Data quite well distributed w.r.t. Mw.
- Most data from rrup < 300km.
- Use Bayesian linear regression (Ordaz et al., 1994) because of limited data. Prior probability distributions
of coefficients are obtained from empirical model of source spectrum with 2 corner frequencies,
frequency-dependent attenuation parameters for the region, duration estimates and random vibration
theory. For the lake-bed stations use this information plus the 1D analytical transfer function using soil
- Compare final coefficients to prior estimates.
- Examine residuals w.r.t. Mw and rrup and find no clear trends.
- Try including H in model but insufficient data to constrain coefficient.
- Compare predicted and observed spectra for all data. Find good match except for a few poorly-recorded