- Ground-motion model is:
where Y is in g, C1 = 0.040311, C2 = 0.417342, C3 = 0.001, C4 = 0.65, C5 = -0.351119 and
C6 = -0.035852 for horizontal PGA and C1 = 0.0015, C2 = 0.8548, C3 = 0.001, C4 = 0.4, C5 = -0.463
and C6 = 0.0006 for vertical PGA.
- Uses two site categories:
S = 0
- Rock, site categories I and II of Iranian building code.
S = 1
- Soil, site categories III and IV of Iranian building code.
- Selection criteria are: i) causative earthquake, earthquake fault (if known) and respective parameters are
determined with reasonable accuracy, ii) PGA of at least one component > 50gal, iii) records from free-field
conditions or ground level of low-rise buildings (< three stories), iv) some aftershocks have been eliminated
to control effect of a few large earthquakes and v) records have been processed with acceptable filter
- Regresses directly on Y not on logarithm of Y . Therefore does not calculate standard deviation in normal
way. Considers the deviation of individual records from predictive equations as being PGA dependent.
Finds that a sigmoidal model fits the data well. Therefore Y = (ab + cxd)∕(b + xd) where Y is the error
term and x is the predicted ground motion, a = 0.038723, b = 0.00207, c = 0.29094 and d = 4.97132 for
horizontal PGA and a = 0.00561, b = 0.0164, c = 0.1648 and d = 1.9524 for vertical PGA.