2.25 A. Patwardhan, K. Sadigh, I.M. Idriss, R. Youngs (1978) reported in Idriss (1978)
- Ground-motion model is:
where y is in cm∕s2, d = 0.864 and f = 0.463 and for path A (rock): A = 157 (for median), A = 186
(for mean), B = 1.04 and E = -1.90, for path A (stiff soil): A = 191 (for median), A = 224 (for mean),
B = 0.823 and E = -1.56 and for path B (stiff soil): A = 284 (for median), A = 363 (for mean), B = 0.587
and E = -1.05 (σ not given).
- Separate equations for two types of path:
- Shallow focus earthquakes (California, Japan, Nicaragua and India), 63 records.
- Subduction (Benioff) zone earthquakes (Japan and South America), 23 earthquakes, 5.3 ≤ Ms ≤ 7.8,
- Use two site categories for path A earthquakes for which derive separate equations:
- Rock: 21 records.
- Stiff soil: 42 records.
Use only stiff soil records for deriving subduction zone equation.
- Most earthquakes for path A have 5 ≤ Ms ≤ 6.7.
- All data corrected. PGA for corrected Japanese and South American records much higher than uncorrected