Functional form chosen to enable modelling of effect of reflections off Moho and surface wave attenuation.
Use two site classes:
Vs,30< 750m∕s or, for 30 stations classified using H/V ratios, f0< 7.5Hz where f0 is peak frequency.
Vs,30> 750m∕s or , for 30 stations classified using H/V ratios, f0> 7.5Hz. 213 records.
Develop models for all data and only soil records.
Data from 573 different stations.
Response parameter is acceleration for 5% damping.
Also develop separate models for regions of Alborz (20 earthquakes and 423 records), Zagros (27
earthquakes and 198 records), East (32 earthquakes and 262 records) and Central South (20 earthquakes
and 175 records). Note that regionalization is limited by lack of data for other regions.
Use data recorded by National Strong Motion Network of Iran from 1987 to 2007.
Select data by criterion of earthquake having being recorded by ≥ 3 stations within 350km.
Most data from Mw< 6.5 and r < 150km.
Insufficient data to constrain model for R > R2 therefore set geometric spreading coefficient to 0.5.
Use Monte Carlo technique to find coefficients.
Fit a and b to functional forms: a1+ a2exp(-a3T) and b1+ b2T + b3T2+ b4T3 respectively. Also present
model assuming a = a1+ a2T + a3T + a4T3.
Plot residuals against repi.
Believe model can be applied for 5 < M < 7.5 and repi< 200km.