- Ground-motion model is:
where Y is in g, a = -1.632, b = 0.304, c = -1, h = 2.7, e = 0 and σ = 0.275.
- Use two site categories:
- V s,30 ≤ 750m∕s, Γ = 0.
- V s,30 > 750m∕s, Γ = 1.
- Note that amount of data available for the Umbria-Marche area in central Italy is sufficiently large to
perform statistical analysis at regional scale.
- Focal depths between 2 and 8.7km. Exclude data from an earthquake that occurred at 47km.
- Select only records from earthquakes with ML ≥ 4.5 recorded at less than 100km.
- Exclude data from Nocera Umbra station because it shows a strong amplification effect due to the presence
of a sub-vertical fault and to highly fractured rocks.
- Uniformly process records using BAP (Basic strong-motion Accelerogram Processing software). Instrument
correct records and band-pass filter records using a high-cut filter between 23 and 28Hz and a bi-directional
Butterworth low-cut filter with corner frequency of 0.4Hz and rolloff parameter of 2.
- Note that can use ML because it does not saturate until about 6.5 and largest earthquake in set is
ML = 5.9.
- More than half of records are from earthquakes with ML ≤ 5.5.
- State that equations should not be used for ML > 6 because of lack of data.
- Use similar regression method as Ambraseys et al. (1996) to find site coefficient, e.