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A derivation of the median ratios between different definitions of horizontal component of ground motions in Central and Eastern United States

Alireza Haji-Soltani, & Shahram Pezeshk

Published August 22, 2016, SCEC Contribution #7049, 2016 SCEC Annual Meeting Poster #263

A single ground motion intensity measure, typically spectral acceleration (SA), is required as the main input in deriving empirical Ground Motion Prediction Equations (GMPEs). There has been a debate for years on which of the two horizontal ground motion orientations would be the most appropriate single horizontal orientation to be used in developing GMPEs. Traditionally, a single horizontal orientation has been used in calculating SA for all periods. The spectrum changes with orientation and using a single orientation to represent two dimensional ground motions may lead to loss of this information. Therefore, different techniques have been proposed in the literature to combine the two horizontal components of ground motions into a scaler definition. Several researchers have studied the ratios between different definitions of horizontal component of ground motions. While the most recent studies produced similar results using different subsets of the NGA West-2 database, it is possible that such ratios may differ for different regions. The purpose of this study is to derive ratios between median values for different definitions of horizontal component of ground motions in central and Eastern United States (CEUS) using a subset of the NGA-East database. These median ratios can be used along with the magnitude and distance scaling factors in a coherent and consistent way when multiple GMPEs are combined in a logic-tree framework in performing Probabilistic Seismic Hazard Analysis (PSHA).

Citation
Haji-Soltani, A., & Pezeshk, S. (2016, 08). A derivation of the median ratios between different definitions of horizontal component of ground motions in Central and Eastern United States. Poster Presentation at 2016 SCEC Annual Meeting.


Related Projects & Working Groups
Seismology