1987 Whittier Narrows-01, Downey - Birchdale

Ground motion information:

NGA Record Sequence Number 614

Magnitude = 6
Closest Distance = 20.8 km
Hypocentral Distance = 21.14 km
Vs30 = 245 m/s
Mechanism = Reverse-oblique

T_p = 0.86 s
PGV = 40.1 cm/s

Orientation of strongest pulse, relative to north = 176 degrees
Orientation of strongest pulse, relative to fault parallel = 76 degrees
Pulse in fault normal direction = 1
Pulse due to directivity = 0

Comments:

Poor directivity geometry, large distance given the amount of rupture between the fault and site

Directivity parameters:

X = 0.26
s = 2.59 km
θ = 80.2

Y = 0.03
d = 0.19 km
φ = 14.1

IDP = 0.02
Rowshandel parameter = -0.16