Chiou and Youngs PEER-NGA Empirical Ground Motion Model for ...

The third condition is represented by specifying the ground motion component to be the
orientation-independent ground motion measure GMRotI50 defined by Boore et al. (2006).
Use of this ground motion measure eliminates recordings for which only a single horizontal
component was obtained. The notable effect of imposing this condition is the elimination of
the Cholame-Shandon Array #2 recording from the 1966 Parkfield earthquake.
The ground motion model developed in this study explicitly accounts for site conditions.
Therefore, recordings from sites for which there is no available information of the local soil
conditions were excluded. These data were limited to a few recordings from earthquakes in
Greece and Turkey.
The regional distribution of the selected recordings is listed in Table 2
Table 2: Regional Distribution of Selected Recordings
Active Region Number of
Number of
Earthquakes Recordings
Alaska 3 57
Armenia 1 1
California 81 1311
Canada 1 3
Georgia 1 5
Greece 8 13
Idaho 2 5
Iran 2 14
Israel 1 1
Italy 8 43
Japan 1 22
the Netherlands 1 3
New Zealand 4 5
Nicaragua 2 2
Russia 1 1
San Salvador 1 2
Taiwan 6 1753
Turkey 7 56
Totals 131 3297
Figure 1 shows the magnitude-distance distribution of the selected recordings. As in most
recent developments of empirical ground motion models for application in California,
recordings from other regions serve the primary roll in providing data at large (M > 7)
magnitudes.
C&Y2006 Page 3