Examining topographic effects from earthquake-induced ground motions: Case study of the Port Hills, New Zealand

Abstract

Many areas of New Zealand reside on topographically irregular terrain (ie, hills, canyons), which influences the ground shaking felt in these areas. Currently, so-called topographic effects are not explicitly considered in conventional ground motion prediction, which results in greater modelling uncertainty. 

This report presents research over the past two years in order to enhance the holistic consideration of topographic effects in ground motion prediction through a combination of experimental data collection and 2D numerical analysis, through to the holistic consideration of topographic effects in 3D ground motion simulation methods. We summarise the technical capability developments in these areas through this small project, and with the international collaborations developed and on-going, where we expect this research to go in the near future.

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Technical Abstract

This report provides a summary of research to enhance capability developments for the explicit modelling of topographic effects in strong ground motion prediction. We consider observations for the 2010-2011 Canterbury earthquakes, as well as undertake ambient vibration field testing to obtain data used to understand topographic amplification in the Christchurch Port Hills. We then perform 2D simulations to corroborate the field testing observations, and then finally generalize to the consideration of topographic effects in 3D ground motion simulations. Through collaborations developed with international research teams we provide a forward look toward developments that we expect to happen in the near future in order to consider this important phenomena in strong ground motion prediction.

Associated Publications:

Seokho Jeong, Brendon A Bradley 2017, Amplification of strong ground motions at Heathcote Valley during the 2010-2011 Canterbury earthquakes: Observation and 1D site response analysis. Soil Dynamics and Earthquake Engineering 100 (2017) 345-356 - doi-0.1016/j.soildyn.2017.06.00