where y is in gal, c1= 2,154,000, c2= 2.10, d1= 0.046, d2= 0.445, e1= 2.515, e2= -0.486, for y = 0.01gσ = 0.5, for y = 0.05g σ = 0.48, for y = 0.10g σ = 0.46 and for y = 0.15g σ = 0.41 (in terms of natural
Use 25 because assume energy centre of Californian earthquakes to be at depth 5km.
Consider two site conditions but do not model:
Rock: (21 records)
Stiff soil: (38 records)
32% of records from San Fernando (9/2/1971) but verifies that relationship is not significantly biased by
Most records within 50km and most from earthquakes with magnitudes of about 6.5.
Recognises that magnitude and distance are not independent variables.
Find b1, b2 and b3 by dividing data according to distance and computing b parameters for each set using
least squares. Find a distinct trend with little scatter.