Hybrid broadband simulation of ground motions from the Canterbury earthquakes

Abstract

The 2010-2011 Canterbury earthquakes were recorded over a dense strong motion network in the near-source region, yielding significant observational evidence of seismic complexities, and a basis for interpretation of multi-disciplinary datasets and induced damage to the natural and built environment. 

This project examines the observed strong motions from these events and retrospective comparisons with both empirical and physics-based ground motion models. Both empirical and physics-based methods provide good predictions of observations at short vibration periods in an average sense. However, observed ground motion amplitudes at specific locations, such as Heathcote Valley, are seen to systematically depart from ‘average’ empirical predictions as a result of near surface stratigraphic and topographic features which are well modelled via site-specific response analyses. 

Significant insight into the long period bias in empirical predictions is obtained from the use of hybrid broadband ground motion simulation. The comparison of both empirical and physics-based simulations against a set of 10 events in the sequence clearly illustrate the potential for simulations to improve ground motion and site response prediction, both at present, and further in the future.

References for final report:

Bradley BA. Systematic ground motion observations in the Canterbury earthquakes and region-specific non-ergodic empirical ground motion modeling. Earthquake Spectra 2015. Vol 31. No 3. pp 1735-1761.

Conference Presentations:

Lee RL, Bradley BA. Investigation of regional quality factors from a New Zealand-wide velocity model. New Zealand Society for Earthquake Engineering Annual Conference. 1-3 April 2016. Christchurch, New Zealand (poster).

Thomson EM, Bradley BA, Lee RL. The Canterbury velocity model (CantVM) version 1. Computational implementation, south island extension, and integration within the UCVM framework. New Zealand Society for Earthquake Engineering Annual Conference. 1-3 April 2016. Christchurch, New Zealand (poster).

Razafindrakoto HNR, Bradley BA, Graves RW. Broadband ground motion simulation of the 2010-2011 Canterbury earthquake sequence. New Zealand Society for Earthquake Engineering Annual Conference. 1-3 April 2016. Christchurch, New Zealand, 8pp.

Bradley BA, Jeong S, Razarfindrakoto HNR. Strong ground motions from the 2010-2011 Canterbury earthquakes and the predictive capability of empirical and physics-based simulation models. 10th Pacific Conference on Earthquake Engineering. 6-8 November 2015. Sydney, Australia. 16pp. Plenary Lecture.

Razafindrakoto HNT, Bradley BA, Thomson EM, Graves RW. Hybrid broadband simulations of the 2010-2011 Canterbury earthquakes. Southern California Earthquake Centre (SCEC) Annual Meeting. 13-16 September 2015. Palm Springs, California, USA. (poster).

Bradley BA, Lee RL, Thomson EM, Ghisetti F, McGann CR, Pettinga J, Hughes MW. 3D Canterbury Velocity Model (CantVM) – Version 1.0. Southern California Earthquake Centre (SCEC) Annual Meeting. 13-16 September 2015. Palm Springs, California, USA. (poster).