- Ground-motion model is:
where PGA is in cm∕s2. For Bucharest azimuth b′ = -0.21056, bM = 1.29099, bR = -0.80404, C = 40 and
σ = 0.52385, for Valeni azimuth b′ = -1.52412, bM = 1.42459, bR = -0.70275, C = 40 and σ = 0.51389
and for Cherna Voda b′ = 4.16765, bM = 1.11724, bR = -1.44067, C = 40 and σ = 0.47607.
- Focal depths, h, between 89 and 131km.
- Incomplete data on local site conditions so not included in study.
- Some strong-motion records are not from free-field locations.
- Uses ρ to characterise the non-homogeneity of region. Includes effect of instrument location w.r.t. the main
direction of propagation of seismic energy, as well as the non-homogeneous attenuation in two orthogonal
directions. ρ = where α is angle between instrument and main direction of
seismic energy or direction of fault projection on surface and a is parameter defining the non-homogeneous
attenuation in two orthogonal directions, or relation between the semi-axes of the ellipse of seismic field.
- Uses a two step method. In first step derive equations for each earthquake using lnPGA = b′0+b1 ln(Re∕ρ).
In the second step the complete Ground-motion model is found by normalizing separately for each
earthquake with a value of ρ defined for that earthquake according to the location for which the equation
- Notes that there is limited data so coefficients could be unreliable.
- Strong-motion records processed by different institutions.