Strong Ground Motion Attenuation Relationships for Subduction Zone Earthquakes

Abstract

We present attenuation relationships for peak ground acceleration and response spectral acceleration for subduction zone interface and intraslab earthquakes of moment magnitude M 5 and greater and for distances of 10 to 500 km. The relationships were developed by regression analysis using a random effects regression model that addresses criticism of earlier regression analyses of subduction zone earthquake motions. We find that the rate of attenuation of peak motions from subduction zone earthquakes is lower than that for shallow crustal earthquakes in active tectonic areas. This difference is significant primarily for very large earthquakes. The peak motions increase with earthquake depth and intraslab earthquakes produce peak motions that are about 50 percent larger than interface earthquakes.