Insights on Ground-Motion Modelling from a Fourier-Spectral Perspective

Synopsis

Roughly a decade ago engineering seismologists spent their time arguing that ground-motions were essentially the same everywhere and that global/regional ergodic models ought to be used for hazard/risk studies. However, since then the evolution of seismic hazard studies has been marked by the strong move from ergodic to partially non-ergodic approaches to ground-motion representation. The key issue in this movement is the tailoring of ground-motion models for site-specific application. This tailoring involves making adjustments to ergodic ground-motion models, and the physical basis for these adjustments is best understood in the Fourier domain.

This talk summarises some recent work that has helped to better understand the relationship between Fourier and response spectra. The implications of this improved understanding include:

• an appreciation of how site-specific adjustments can be made to ergodic models so that both median predictions and variability are appropriately defined;
• improved representation of variance structures in ground-motion model development; and,
• reconciliation of differences in estimated and implied stress drop variability, among other things.

The talk aims to provide a summary of these implications and should be of interest to anyone involved with site-specific seismic hazard analyses.

About the speaker

Dr Peter J Stafford is a Reader in Engineering Seismology & Earthquake Engineering at the Department of Civil & Environmental Engineering at Imperial College London. He obtained his BE(Hons) and PhD from the University of Canterbury in New Zealand before initially joining Imperial College as a postdoc in 2006 and becoming a member of faculty there in 2007. Over the past decade he has taught late-stage undergraduate and graduate (MSc & PhD) courses in subjects related to seismic hazard and risk, structural dynamics and applied probability. His principle areas of investigation and expertise relate to the fields of Engineering Seismology and Earthquake Engineering, but he also maintains active research interests in applications of probabilistic methods to engineering applications (Structural Reliability Theory), and applied Structural Dynamics. He has significant industrial experience conducting hazard and risk analyses for critical infrastructure projects, as well as developing earthquake loss models for insurance and reinsurance applications. He is currently a member of the editorial boards of the Bulletin of the Seismological Society of America and Earthquake Spectra.

Further information

This evening meeting is organised by SECED and chaired by Damian Grant (Arup). Non-members of the society are welcome to attend. Attendance at this meeting is free. Seats are allocated on a first come, first served basis. Tea and biscuits will be served from 5.30pm - 6pm. For further information, please contact Brendan van Rooyen (tel. 020 7665 2229).