BeckerFraserPhotos April 2011 photograph 796

Images, UC QuakeStudies

Photograph captioned by BeckerFraserPhotos, "The balcony of a resident's house hanging precariously over the edge of a cliff in Sumner after rocks at the top were dislodged during the February 22 earthquake".

BeckerFraserPhotos February 2011 photograph 332

Images, UC QuakeStudies

A large crack in the ground at Sullivan Park in Avonside which has resulted from the 4 September 2010 earthquake. Remnants of liquefaction silt can be seen around the edges of the crack.

BeckerFraserPhotos February 2011 photograph 333

Images, UC QuakeStudies

A large crack in the ground at Sullivan Park in Avonside which has resulted from the 4 September 2010 earthquake. Remnants of liquefaction silt can be seen around the edges of the crack.

BeckerFraserPhotos February 2011 photograph 330

Images, UC QuakeStudies

A large crack in the ground at Sullivan Park in Avonside which has resulted from the 4 September 2010 earthquake. Remnants of liquefaction silt can be seen around the edges of the crack.

BeckerFraserPhotos May 2013 photograph 108

Images, UC QuakeStudies

A view looking south down Waygreen Avenue in New Brighton. The footpath is covered with weeds and silt from liquefaction. Flooding can be seen along the edges of the road. A road cone stands in the middle of the road.

BeckerFraserPhotos February 2011 photograph 269

Images, UC QuakeStudies

A gutter on Bracken Street in Avonside showing cracks from the 4 September 2010 earthquake. The edges of the footpath above it have fallen away, and the gutter has filled with the loose gravel which was used to fill pot holes in the road.

BeckerFraserPhotos December 2011 photograph 0276

Images, UC QuakeStudies

An aerial photograph of the Christchurch City Council Civic Offices and surrounding buildings. The photograph has been captioned by BeckerFraserPhotos, "The River Avon runs through this photograph and marks the western edge of the red zone".

BeckerFraserPhotos September 2010 photograph 138

Images, UC QuakeStudies

Detail of the side of the front wall of St Mary & St Athanaslos church on Edgeware Road. The edge of the wall has separated from the bricks and is threatening to topple. Cracks can be seen running diagonally through the brick wall, the rest of the wall missing above.

Paul and Sam Corliss's Street Art Photograph (2015:03:21 12:31:24)

Images, UC QuakeStudies

A photograph of street artwork painted on a box on the corner of Madras Street and St Asaph Street. The artwork depicts a person in a beret hanging on to the edge of the painting, pulling it down to reveal a blue sky.

Paul and Sam Corliss's Street Art Photograph (2015:03:21 12:31:25)

Images, UC QuakeStudies

A photograph of street artwork painted on a box on the corner of Madras Street and St Asaph Street. The artwork depicts a person in a beret hanging on to the edge of the painting, pulling it down to reveal a blue sky.

Paul and Sam Corliss's Street Art Photograph (2015:03:21 12:31:26)

Images, UC QuakeStudies

A photograph of street artwork painted on a box on the corner of Madras Street and St Asaph Street. The artwork depicts a person in a beret hanging on to the edge of the painting, pulling it down to reveal a blue sky.

Paul and Sam Corliss's Street Art Photograph (2015:03:21 23:54:10)

Images, UC QuakeStudies

A photograph of street artwork painted on a box on the corner of Madras Street and St Asaph Street. The artwork depicts a person in a beret hanging on to the edge of the painting, bringing it down to reveal a blue sky.

BeckerFraserPhotos October 2010 photograph 061

Images, UC QuakeStudies

A brick house on Centaurus Road with damage to the top left window and "Danger Keep Out" tape around the edge. A yellow sign on the front window indicates that the building should only be entered for "Restricted Use". This means it has faired better than the brick house next door which is red-stickered.

BeckerFraserPhotos December 2011 photograph 0289

Images, UC QuakeStudies

An aerial photograph of the Christchurch central city. The photograph has been captioned by BeckerFraserPhotos, "High Street runs across this photograph in the top third from the old Majestic Theatre at the intersection of Manchester and Lichfield Streets to the intersection of Madras and St Asaph Street which is just beyond the edge of the photo".

Simulation and Validation of Topographic Effectds on Mt Pleasant, Christch…

Research papers, University of Canterbury Library

Damage distribution maps from strong earthquakes and recorded data from field experiments have repeatedly shown that the ground surface topography and subsurface stratigraphy play a decisive role in shaping the ground motion characteristics at a site. Published theoretical studies qualitatively agree with observations from past seismic events and experiments; quantitatively, however, they systematically underestimate the absolute level of topographic amplification up to an order of magnitude or more in some cases. We have hypothesized in previous work that this discrepancy stems from idealizations of the geometry, material properties, and incident motion characteristics that most theoretical studies make. In this study, we perform numerical simulations of seismic wave propagation in heterogeneous media with arbitrary ground surface geometry, and compare results with high quality field recordings from a site with strong surface topography. Our goal is to explore whether high-fidelity simulations and realistic numerical models can – contrary to theoretical models – capture quantitatively the frequency and amplitude characteristics of topographic effects. For validation, we use field data from a linear array of nine portable seismometers that we deployed on Mount Pleasant and Heathcote Valley, Christchurch, New Zealand, and we compute empirical standard spectral ratios (SSR) and single-station horizontal-to-vertical spectral ratios (HVSR). The instruments recorded ambient vibrations and remote earthquakes for a period of two months (March-April 2017). We next perform two-dimensional wave propagation simulations using the explicit finite difference code FLAC. We construct our numerical model using a high-resolution (8m) Digital Elevation Map (DEM) available for the site, an estimated subsurface stratigraphy consistent with the geomorphology of the site, and soil properties estimated from in-situ and non-destructive tests. We subject the model to in-plane and out-of-plane incident motions that span a broadband frequency range (0.1-20Hz). Numerical and empirical spectral ratios from our blind prediction are found in very good quantitative agreement for stations on the slope of Mount Pleasant and on the surface of Heathcote Valley, across a wide range of frequencies that reveal the role of topography, soil amplification and basin edge focusing on the distribution of ground surface motion.