TY  - JOUR
A1  - Kotha, Sreeram Reddy
A1  - Bindi, Dino
A1  - Cotton, Fabrice
T1  - From Ergodic to Region- and Site-Specific Probabilistic Seismic Hazard Assessment: Method Development and Application at European and Middle Eastern Sites
JF  - Earthquake spectra : the professional journal of the Earthquake Engineering Research Institute
N2  - The increasing numbers of recordings at individual sites allows quantification of empirical linear site-response adjustment factors (delta S2S(s)) from the ground motion prediction equation (GMPE) residuals. The delta S2S(s) are then used to linearly scale the ergodic GMPE predictions to obtain site-specific ground motion predictions in a partially non-ergodic Probabilistic Seismic Hazard Assessment (PSHA). To address key statistical and conceptual issues in the current practice, we introduce a novel empirical region-and site-specific PSHA methodology wherein, (1) site-to-site variability (phi(S2S)) is first estimated as a random-variance in a mixed-effects GMPE regression, (2) delta S2S(s) at new sites with strong motion are estimated using the a priori phi(S2S), and (3) the GMPE site-specific single-site aleatory variability sigma(ss,s) is replaced with a generic site-corrected aleatory variability sigma(0). Comparison of region- and site-specific hazard curves from our method against the traditional ergodic estimates at 225 sites in Europe and Middle East shows an approximate 50% difference in predicted ground motions over a range of hazard levels-a strong motivation to increase seismological monitoring of critical facilities and enrich regional ground motion data sets.
Y1  - 2017
U6  - https://doi.org/10.1193/081016EQS130M
SN  - 8755-2930
SN  - 1944-8201
VL  - 33
SP  - 1433
EP  - 1453
PB  - Earthquake Engineering Research Institute
CY  - Oakland
ER  - 
TY  - JOUR
A1  - Kotha, Sreeram Reddy
A1  - Bindi, Dino
A1  - Cotton, Fabrice
T1  - Site-Corrected Magnitude- and Region-Dependent Correlations of Horizontal Peak Spectral Amplitudes
JF  - Earthquake spectra : the professional journal of the Earthquake Engineering Research Institute
N2  - Empirical correlations of horizontal peak spectral amplitudes (PSA) are modeled using the total-residuals obtained in a ground motion prediction equation (GMPE) regression. Recent GMPEs moved toward partially non-ergodic region-and site-specific predictions, while the residual correlation models remained largely ergodic. Using mixed-effects regression, we decompose the total-residuals of a pan-European GMPE into between-event, between-site, and event-and-site corrected residuals to investigate the ergodicity in empirical PSA correlations. We first observed that the between-event correlations are magnitude-dependent, partially due to the differences in source spectra, and influence of stress-drop parameter on small and large events. Next, removing the between-site residuals from within-event residuals yields the event-and-site corrected residuals which are found to be region-dependent, possibly due to the regional differences in distance-decay of short period PSAs. Using our site-corrected magnitude- and region-dependent correlations, and the between-site residuals as empirical site-specific ground motion adjustments, we compute partially non-ergodic conditional mean spectra at four well-recorded sites in Europe and Middle Eastern regions.
Y1  - 2017
U6  - https://doi.org/10.1193/091416EQS150M
SN  - 8755-2930
SN  - 1944-8201
VL  - 33
SP  - 1415
EP  - 1432
PB  - Earthquake Engineering Research Institute
CY  - Oakland
ER  -