- Ground-motion model is: where Δ is ‘representative’ distance, S is ‘size’ of fault, S0 is coherence radius of source and v is component
orientation (v = 0 for horizontal, v = 1 for vertical).
- Response parameter is pseudo-velocity for 0, 2, 5, 10 and 20% damping.
- Consider three geological site conditions:
s = 0
- Sediment: ⇒ S(1) = 0,S(2) = 0, 151 records.
s = 1
- Intermediate sites: ⇒ S(1) = 1,S(2) = 0, 106 records.
s = 2
- Basement rock: ⇒ S(1) = 0,S(2) = 1, 54 records.
- Consider three local site categories but only retain two:
sL = 0
- Rock: ⇒ SL(1) = 0, 100 records.
sL = 1
- Stiff soil: ⇒ SL(1) = 1, 205 records.
- Cannot include those records from deep soil sites (sL = 2) because only six records.
- Most earthquakes are shallow, depth H < 25km.
- Most records have epicentral distances, R < 50km.
- Most have magnitudes between 3 and 6.
- Only use records with high signal-to-noise ratio. Quality of records is not adequate for response spectrum
calculation outside range 0.04 to 2s.
- Analysis performed using residue 2-step method. In first step use only records from M ≥ 4.25 to force a
concave form to magnitude scaling (if all records used then find a convex parabola), sL parameter is not
included. In second step find sL dependence from residuals of first stage including all magnitudes.
- Give expressions to describe distribution of residuals so that can find confidence limits, unlike normal
standard deviation based method, see Trifunac (1980).
- Note difference between western USA and Yugoslavian ground motions.