- Ground-motion model is:
- Response parameters are pseudo-acceleration, PSA, and pseudo-velocity, PSV, for 5% damping.
- Use three soil conditions (revised when cross hole information was available):
S = 0
- Hard and rock sites, 50 records.
S = 1
- Intermediate soil, 10 records.
S = 2
- Soft soil, 12 records.
- Use ML because most suitable for distance range of majority of records.
- Try including c5S term but find low significance values for c5. Repeat regression for each soil category
separately. Give results when coefficient of determination R2 > 0.80, standard errors < 25% and coefficients
have high significance levels.
- For PSA for S = 0 give coefficients for all periods, for S = 1 give coefficients for 0.17 to 0.2s and for S = 2
give coefficients for 1 to 10s.
- Also consider Friuli records (4.2 ≤ ML ≤ 6.5, epicentral distances between 2 and 192km, 14 records for
S = 0, 23 records for S = 1 and 16 records for S = 2).
- Note need to include term in model reflecting explicitly local amplification dependent on natural period
of soil as well as predominant period of incident radiation to bed rock.