by Paul Somerville, Nancy Collins, Robert Graves, and Arben Pitarka
Somerville, Paul, Nancy Collins, Robert Graves and Arben Pitarka (2003). Development of an Engineering Model of Basin Generated Surface Waves. SMIP03
Seminar on Utilization of Strong-Motion Data, p. 1 - 20.
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We have developed a modification to the ground motion model of Abrahamson et al. (1997) that takes into account the effects of basin generated
surface waves. The main feature of our model is that for response spectral accelerations at periods of 4 and 5 seconds, the Abrahamson and Silva
(1997) model for soil sites should be scaled by a factor of 1.65 in order to represent the ground motions on soil sites located within
sedimentary basins. Our finding that no scaling of the Abrahamson and Silva (1997) model is required for periods shorter than 4 seconds
reflects the fact that most of the deep soil recordings on which that model is based come from sedimentary basins. The fact that our first
order model does not have a dependence on distance to the basin edge or the depth of the basin makes it easily applicable in ground motion
calculations, especially those for probabilistic seismic hazard analyses, which typically involve the calculation of ground motions from many
different scenario earthquakes occurring on a variety of faults surrounding the site. We have identified many second order basin effects that
are not quantified in our first order model of basin effects.