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

data are consistent with strong motion data in other active tectonic regions (e.g. Italy –
Sabetta and Pugliese, 1996; the Mediterranean basin – Ambraseys et al., 1996; Japan –
Fukushima and Tanaka, 1990). It has also been common to include ground motions from
earthquakes such as Gazli, 1976, and Tabas, 1978, in developing ground motion models for
application in California (e.g. Abrahamson and Silva, 1997, Campbell, 1997, Sadigh et al.
1997). In this study we start with the hypothesis that the ground motions from these separate
active tectonic regions are similar and can be combined. We examine this hypothesis during
model development.
Table 1: Excluded Earthquakes
EQID EQNAME Comment
0003 Humbolt Bay Gorda plate
0005 Northwest Calif-01 Gorda plate
0007 Northwest Calif-02 Gorda plate
0008 Northern Calif-01 Gorda plate
0011 Northwest Calif-03 Gorda plate
0013 Northern Calif-02 Gorda plate
0017 Northern Calif-03 Gorda plate
0022 Northern Calif-04 Gorda plate
0026 Northern Calif-05 Gorda plate
0035 Northern Calif-07 Gorda plate
0067 Trinidad Gorda plate
0071 Taiwan SMART1(5) Deep offshore event
0084 Trinidad offshore Gorda plate
0086 Taiwan SMART1(25) Deep offshore event
0093 Pelekanada, Greece Deep event
0095 Taiwan SMART1(33) Deep offshore event
0109 Taiwan SMART1(45) Offshore event
0142 St Elias, Alaska Subduction interface event
0153 Northwest China-01 Poorly known event
0154 Northwest China-02 Poorly known event of moderate depth
0155 Northwest China-03 Poorly known event of moderate depth
0156 Northwest China-04 Poorly known event of moderate depth
To meet the second condition, recordings made in large buildings and at depth were
removed. These are indicted by the “Geomatrix” C1 site codes of ‘C’, ‘D’, ‘E’, ‘F’, ‘G’, and
‘H’ (non-abutment sites). The exclusion of basement and large building/massive foundation
recordings eliminates several additional earthquakes, notably the 1935 Helena records and a
number from Imperial Valley recorded at the old Imperial Valley Irrigation District site. We
included records from sites that have been characterized as having topographic effects (e.g.
Tarzana Cedar Hill Nursery, Pacoima Dam left abutment) and dam abutments in general.
Our rational for including these records is that the effect of topography has not been
systematically studied for all of the records in the database and many of the other recording
stations may have topographic enhancement or suppression of ground motions. Therefore,
topographic effects are considered to be part of the variability introduced into ground
motions by travel path and site effects.
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