Site amplification effects at Heathcote Valley, New Zealand, during the 2010-2011 Canterbury earthquakes

Seokho Jeong, & Brendon A. Bradley

Submitted August 9, 2016, SCEC Contribution #6591, 2016 SCEC Annual Meeting Poster #283

This poster presents a quantitative case study on the role of near surface site effects on the ground motion intensities at Heathcote Valley school station (HVSC), New Zealand, during the 2010-2011 Canterbury earthquake sequence, accounting for the surface topography, the realistic geological structure, and the non-linear constitutive behaviour of soils.

Simulations show that ground motions at HVSC are amplified in a wide band of frequencies, and the simulated ground motion amplitude in high frequencies (i.e. higher than the site fundamental frequency) is sensitive to the various modelling assumptions.

The result demonstrates that 1D simulations without proper consideration of the basin structure tend to underestimate the site response, likely due to its inability to model surface waves caused by the inclined soil-rock interface. Comparison of linear-elastic and non-linear analyses suggests that the non-linear hysteretic response of soils dissipates significant energy for strong shaking events. Adoption of a simpler depth-independent soil model revealed that such a minor simplification can lead to a substantial underestimation of ground motion intensity. Simulations also suggest that the pressure-dependent (no tension) nonlinear constitutive behaviour of soils, combined with energetic near-field vertical motions, might be the primary mechanism of strong asymmetrical acceleration pulses observed during the February 2011 Christchurch earthquake.

Citation
Jeong, S., & Bradley, B. A. (2016, 08). Site amplification effects at Heathcote Valley, New Zealand, during the 2010-2011 Canterbury earthquakes. Poster Presentation at 2016 SCEC Annual Meeting.


Related Projects & Working Groups
Ground Motion Simulation Validation (GMSV)