Scientia Iranica

Scientia Iranica

Attenuation Relation for Near Field Shallow Crustal Earthquakes Using NGA-West Database with Mixed-Effect Model in Comparison with Attenuation Relations for Iran

Document Type : Research Article

Authors
Alirez Shokran Neam
Touraj Taghikhany
Department of Civil and Environmental Engineering, Amirkabir University of Technology, Tehran, Iran
10.24200/sci.2017.4152
Abstract
This article presents a new empirical equation for the estimation of horizontal strong ground motions caused by shallow crustal earthquakes. This model is developed empirically by regression of the database which is used by the NGA-West2 GMPE developers with a fault rupture distance less than 60 kilometers. The data set consisted of corrected and processed accelerograms of 1545 strong-motion records of earthquakes between Mw 5.2 and 7.9. Model is a function of earthquake magnitude, distance from source to site, local average shear wave velocity, nonlinear soil response, sediment depth, rupture dip, faulting mechanism and hanging wall effect. This equation was derived by a stable algorithm for regression analysis called mixed effect model. The algorithm was used to develop PGA and PSA (T1) for periods from 0.01 to 10.0 seconds. Major differences between this model with recent developed attenuation relations for the world and Iran were observed for large-magnitude ground motions which were recorded at small-to-moderate distances from seismic source. The results showed that the near-field affected the predicted values especially in soil sites. Moreover, comparison with the attenuation relations developed by Iranian data set confirmed that the equation in this region is sensitive more to distance than to other parameters.  
 
Keywords
Empirical attenuation relationship
NGA
Mixed effects model
Nonlinear model
Iran plateau
Subjects
Scientia Iranica
Volume 24, Issue 5
Transactions on Civil Engineering (A)
September and October 2017
Pages 2183-2201

  • Receive Date 24 August 2014
  • Revise Date 26 December 2015
  • Accept Date 25 July 2016