- See Section 2.275.
- Response parameter is pseudo-acceleration (PSA) for 5% damping.
- If PSA < PGA for T ≤ 0.25s then set PSA equal to PGA, to be consistent with definition of PSA (occurs
for large distances and small magnitudes).
- Due to cut-off frequencies used number of records available for periods > 4–5s falls off significantly. Majority
of earthquakes at long periods are for 6.5 ≤ M ≤ 7.9 and 70% are from 1999 Chi-Chi earthquake.
- To extend model to longer periods and small magnitudes constrain the magnitude-scaling term using
empirical observations and simple seismological theory.