Empirical equations for the prediction of PGA and pseudo spectral accelerations using Iranian strong

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Empirical equations for the prediction of PGA and pseudo spectral accelerations using Iranian strong-motion data

H. Zafarani & Lucia Luzi & Giovanni Lanzano &

M. R. Soghrat

Abstract A recently compiled, comprehensive, and

good-quality strong-motion database of the Iranian

earthquakes has been used to develop local empirical

equations for the prediction of peak ground

acceleration (PGA) and 5%-damped pseudospectral

accelerations (PSA) up to 4.0 s. The equations

account for style of faulting and four site

classes and use the horizontal distance from the

surface projection of the rupture plane as a distance

measure. The model predicts the geometric mean of

horizontal components and the vertical-to-horizontal

ratio. A total of 1551 free-field acceleration time

histories recorded at distances of up to 200 km from

200 shallow earthquakes (depth < 30 km) with moment

magnitudes ranging from Mw 4.0 to 7.3 are

used to perform regression analysis using the random

effects algorithm of Abrahamson and Youngs

(Bull Seism Soc Am 82:505–510, 1992), which

considers between-events as well as within-events

errors. Due to the limited data used in the development

of previous Iranian ground motion prediction

equations (GMPEs) and strong trade-offs between

different terms of GMPEs, it is likely that the previously

determined models might have less precision

on their coefficients in comparison to the current

study. The richer database of the current study

allows improving on prior works by considering

additional variables that could not previously be

adequately constrained. Here, a functional form used

by Boore and Atkinson (Earthquake Spect 24:99–

138, 2008) and Bindi et al. (Bull Seism Soc Am

9:1899–1920, 2011) has been adopted that allows

accounting for the saturation of ground motions at

close distances. A regression has been also performed

for the V/H in order to retrieve vertical

components by scaling horizontal spectra. In order

to take into account epistemic uncertainty, the new

model can be used along with other appropriate

GMPEs through a logic tree framework for seismic

hazard assessment in Iran and Middle East region.

 

Keywords Ground motion prediction equations . Strong

motion . PSHA. V/H ratio . Iran

 

جدیدترین رابطه کاهندگی ارائه شده برای فلات  ایران توسط دکتر زعفرانی و همکاران (2017)

 

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