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.
Today (04/09/14) marks the fourth anniversary since the first earthquake rocked the city and greater Christchurch area. That first quake was magnitude 7.1, and luckily there was only one fatality (possible a heart attack). Since then we have had over 14,000 quakes, most very small in magnitude, but well over 500 of magnitude 4 or greater. 5...
Another city walk around, this time with my brother-in-law from Auckland. Also went to the Quake City exhibition in the city organised by the Canterbury Museum. First fine day for a while.
Is it to "ward" off evil spirits?.
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Looking across to the Town Hall. Will it stay or will it go?
Earthquake damage. As a result of the September 2010 earthquake, with further damage from the February 2011 event.
Worcester Blvd. Lawrence Roberts works for Photo & Video in Christchurch, suppliers of much of my photo gear in exchange for cash!
At least two broken pieces from the Scott statue rest in the Canterbury Museum. The statue toppled in the 22nd February 2011 earthquake.
Prior to the earthquakes the stone wall at right was near road level. Now it is about 1.5m (4-5ft) lower.
Verandah roof of former Central Library on left. Rubble is from the former Farmers building and carpark.
Earthquake damage. As a result of the September 2010 earthquake, with further damage from the February 2011 event.
Nearing the end of demolition of the Westend Jewellers site on the corner of Worcester and Manchester Streets, Christchurch. Badly damaged in the September 4th earthquake.
Castle Rock above Heathcote, showing damage (and two very large pieces in the foreground) that came down during the 7.1 quake on 4th September.
Two of the large boulders (larger than a house or two) that came down from Castle Rock (see the fence in front of the boulders).
Nearly two weeks after the 7.1 earthquake, and a week after demolition started, this is the end of The Valley Inn in Heathcote.
The pumping station at the corner of New Brighton Road and Palmers Road. New Brighon Road is still closed (2 weeks after quake) at this point.
Built in the early 1960s for the Lyttelton Road Tunnel, it was severley damaged in the February 2011 earthquake and is not currently used.
The last pile of liquefied silt to be cleaned up, from our lawn.
Post-tensioned timber technology was originally developed and researched at the University of Canterbury (UC) in New Zealand in 2005. It can provide a low-damage seismic design solution for multi-storey mass timber buildings. Since mass timber products, such as cross-laminated timber (CLT), have high in-plane stiffness, a post-tensioned timber shear wall will deform mainly in a rocking mechanism. The moment capacity of the wall at the base is commonly determined using the elastic form of the Modified Monolithic Beam Analogy (MMBA). In the calculation of the moment capacity at the wall base, it is critical to accurately predict the location of the neutral axis and the timber compressive stress distribution. Three 2/3 scale 8.6m tall post-tensioned CLT walls were experimentally tested under quasi-static cyclic loading – both uni-directional and bi-directional- in this study. These specimens included a single wall, a coupled wall, and a C-shaped core-wall. The main objective was to develop post-tensioned C-shaped timber core-walls for tall timber buildings with enhanced lateral strength and stiffness. To better understand the timber compressive stress distributions at the wall base, particle tracking technology (PTT) technology was applied for the first time to investigate the behaviour of the compression toe. Previous post-tensioned timber testing primarily used the displacement measurements to determine the timber compressive behavior at the wall base or rocking interfaces. However, by using PTT technology, the timber strain measurements in the compression zone can be much more accurate as PTT is able to track the movement of many particles on the timber surface. This paper presents experimental testing results of post-tensioned CLT walls with a focus on capturing timber compressive behavior using PTT. The PTT measurements were able to better capture small base rotations which occurred at the onset of gap opening and capture unexpected phenomena in core-wall tests. The single wall test result herein presented indicates that while the MMBA could predict the moment rotation behavior with reasonable accuracy, the peak strain response was under predicted in the compression toe. Further detailed study is required to better understand the complex strain fields generated reflective of the inherent cross-thickness inhomogeneity and material variability of CLT.
Of what many in Christchurch know as the Millers building, but for many recent years was the home to the Christchurch City Council, till just a week or two before the first earthquake of 2010. Now, in mid-2014 it is finally being demolished after nearly 45 months empty. A bus is leaving the new (temporary) bus exchange onto Tuam Street. But n...
Another city walk around, this time with my brother-in-law from Auckland. Also went to the Quake City exhibition in the city organised by the Canterbury Museum. First fine day for a while. For 36 years I worked in a now gone building where that red car is parked (on the left). and would have walked this route thousands of times, yet now it is...
Another city walk around, this time with my brother-in-law from Auckland. Also went to the Quake City exhibition in the city organised by the Canterbury Museum. First fine day for a while. This bus is used as a chocolate restaurant, and is parked next to the Pallet Pavilion on the site of the old Park Royal Hotel.
The site of the Robert Falcon Scott statue. Here is what it looked like before (lining up ICE from POLICE on the Police building) www.flickr.com/photos/johnstewartnz/5921425414/in/set-721...
When this building was first brought on site I spent a few hours removing the tape/paper that had been covering every window.
Cathedral of the Blessed Sacrameny aka Christchurch Basilica
Closed due to earthquake damage. But it looks in better condition than the building I work in!
Looking across several properties to a yet to demolished (or possibly removed) house on Seabreeze Close, Pacific Park, Bexley.
A historic plate smashed in the February Christchurch earthquake. Ashley Gorge Scenic Reserve was established by my Great-Grandmother (maternal) many years ago.