File Reference: CCL-CE-2013-09-30-EQNZ-2010.JPG Photo taken by G. Coster From the collection of Christchurch City Libraries
A photograph of a colourful brick wall and a spiral pattern on the ground at New Brighton Mall. There is also a red and black rug rolled up and laid down on the ground.
A photograph of a detail of street art on Fitzgerald Avenue. The work was created by DEOW on the back wall of AJ Glass, for the "From the Ground Up" project.
A photograph of street art on Byron Street in Sydenham. The artworks were created by South Bound (left) and Leeya Jet (right) as part of the "From the Ground Up" art project.
A photograph of a detail of street art on Fitzgerald Avenue. The work was created by DEOW on the back wall of AJ Glass, for the "From the Ground Up" project.
Large cracks in the ground along Avonside Drive.
Large cracks in the ground along Avonside Drive.
This paper presents on-going challenges in the present paradigm shift of earthquakeinduced ground motion prediction from empirical to physics-based simulation methods. The 2010-2011 Canterbury and 2016 Kaikoura earthquakes are used to illustrate the predictive potential of the different methods. On-going efforts on simulation validation and theoretical developments are then presented, as well as the demands associated with the need for explicit consideration of modelling uncertainties. Finally, discussion is also given to the tools and databases needed for the efficient utilization of simulated ground motions both in specific engineering projects as well as for near-real-time impact assessment.
This one was really flowing out of the ground.
A photograph captioned by Paul Corliss, "Ground culinary centre, Lyttelton".
Hybrid broadband simulation methods typically compute high-frequency portion of ground-motions using a simplified-physics approach (commonly known as “stochastic method”) using the same 1D velocity profile, anelastic attenuation profile and site-attenuation (κ0) value for all sites. However, these parameters relating to Earth structure are known to vary spatially. In this study we modify this conventional approach for high-frequency ground-shaking by using site-specific input parameters (referred to as “site-specific”) and analyze improvements over using same parameters for all sites (referred to as “generic”). First, we theoretically understand how different 1D velocity profiles, anelastic attenuation profiles and site-attenuation (κ0) values affects the Fourier Acceleration Spectrum (FAS). Then, we apply site-specific method to simulate 10 events from the 2010-2011 Canterbury earthquake sequence to assess performance against the generic approach in predicting recorded ground-motions. Our initial results suggest that the site-specific method yields a lower simulation standard deviation than generic case.
A large crack in the ground at Sullivan Park in Avonside.
A large crack in the ground at Sullivan Park in Avonside.
A large crack in the ground at Sullivan Park in Avonside.
A large crack in the ground at Sullivan Park in Avonside.
A photograph of a member of the Wellington Emergency Management Office on the ground floor of the Crowne Plaza Hotel. Sections of the ceiling and plaster dust have fallen onto the ground and there is a large crack in the wall to the right.
A photograph captioned by BeckerFraserPhotos, "Moira Fraser standing beside a bus stop sign in Bower Avenue (near the intersection with New Brighton Road) to demonstrate how much this pole has sunk into the ground. Note the marker with two round luminous spots which is at ground level and compare it with the next photo".
We present ground motion simulations of the Porters Pass (PP) fault in the Canterbury region of New Zealand; a major active source near Christchurch city. The active segment of the PP fault has an inferred length of 82 km and a mostly strike-slip sense of movement. The PP fault slip makes up approximately 10% of the total 37 mm/yr margin-parallel plate motion and also comprises a significant proportion of the total strain budget in regional tectonics. Given that the closest segment of the fault is less than 45 km from Christchurch city, the PP fault is crucial for accurate earthquake hazard assessment for this major population centre. We have employed the hybrid simulation methodology of Graves and Pitarka (2010, 2015), which combines low (f<1 Hz) and high (f>1 Hz) frequencies into a broadband spectrum. We have used validations from three moderate magnitude events (𝑀𝑤4.6 Sept 04, 2010; 𝑀𝑤4.6 Nov 06, 2010; 𝑀𝑤4.9 Apr 29, 2011) to build confidence for the 𝑀𝑤 > 7 PP simulations. Thus far, our simulations include multiple rupture scenarios which test the impacts of hypocentre location and the finite-fault stochastic rupture representation of the source itself. In particular, we have identified the need to use location-specific 1D 𝑉𝑠/𝑉𝑝 models for the high frequency part of the simulations to better match observations.
This poster discusses several possible approaches by which the nonlinear response of surficial soils can be explicitly modelled in physics-based ground motion simulations, focusing on the relative advantages and limitations of the various methodologies. These methods include fully-coupled 3D simulation models that directly allow soil nonlinearity in surficial soils, the domain reduction method for decomposing the physical domain into multiple subdomains for separate simulation, conventional site response analysis uncoupled from the simulations, and finally, the use of simple empirically based site amplification factors We provide the methodology for an ongoing study to explicitly incorporate soil nonlinearity into hybrid broadband simulations of the 2010-2011 Canterbury, New Zealand earthquakes.
This poster presents work to date on ground motion simulation validation and inversion for the Canterbury, New Zealand region. Recent developments have focused on the collection of different earthquake sources and the verification of the SPECFEM3D software package in forward and inverse simulations. SPECFEM3D is an open source software package which simulates seismic wave propagation and performs adjoint tomography based upon the spectral-element method. Figure 2: Fence diagrams of shear wave velocities highlighting the salient features of the (a) 1D Canterbury velocity model, and (b) 3D Canterbury velocity model. Figure 5: Seismic sources and strong motion stations in the South Island of New Zealand, and corresponding ray paths of observed ground motions. Figure 3: Domain used for the 19th October 2010 Mw 4.8 case study event including the location of the seismic source and strong motion stations. By understanding the predictive and inversion capabilities of SPECFEM3D, the current 3D Canterbury Velocity Model can be iteratively improved to better predict the observed ground motions. This is achieved by minimizing the misfit between observed and simulated ground motions using the built-in optimization algorithm. Figure 1 shows the Canterbury Velocity Model domain considered including the locations of small-to-moderate Mw events [3-4.5], strong motion stations, and ray paths of observed ground motions. The area covered by the ray paths essentially indicates the area of the model which will be most affected by the waveform inversion. The seismic sources used in the ground motion simulations are centroid moment tensor solutions obtained from GeoNet. All earthquake ruptures are modelled as point sources with a Gaussian source time function. The minimum Mw limit is enforced to ensure good signal-to-noise ratio and well constrained source parameters. The maximum Mw limit is enforced to ensure the point source approximation is valid and to minimize off-fault nonlinear effects.
A photograph of a large crack in the ground caused by liquefaction.
A photograph of the earthquake damage to the Christchurch Chinese Methodist Church on Papanui Road. The gable walls have crumbled, bricks spilling onto the ground. The tower has been removed and braced on the ground in front. Cordon fencing has been placed around the building. Parts of the fence have been decorated with hearts and the word 'love'.
A woman inspects a large crack in the ground near the side of the road.
The fenced-off site of Ground Culinary Centre on London Street in Lyttelton.
Photograph captioned by BeckerFraserPhotos, "Book Warehouse, ground floor, 232 Cashel Street".
Photograph captioned by BeckerFraserPhotos, "Ground floor Clarendon Tower, 78 Worcester Street".
Photograph captioned by BeckerFraserPhotos, "Ground floor Clarendon Tower, 78 Worcester Street".
An usual thing to see coming from the ground in Hoon Hay, Christchurch.
Diggers on a demolition site on Kilmore Street. One is drilling into the ground.
The ground at this residential property on New Brighton Road is completely water-logged.