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Research papers, The University of Auckland Library

The region in and around Christchurch, encompassing Christchurch city and the Selwyn and Waimakariri districts, contains more than 800 road, rail, and pedestrian bridges. Most of these bridges are reinforced concrete, symmetric, and have small to moderate spans (15–25 m). The 22 February 2011 moment magnitude (Mw) 6.2 Christchurch earthquake induced high levels of localized ground shaking (Bradley and Cubrinovski 2011, page 853 of this issue; Guidotti et al. 2011, page 767 of this issue; Smyrou et al. 2011, page 882 of this issue), with damage to bridges mainly confined to the central and eastern parts of Christchurch. Liquefaction was evident over much of this part of the city, with lateral spreading affecting bridges spanning both the Avon and Heathcote rivers.

Research papers, The University of Auckland Library

The 2011, 6.3 magnitude Christchurch earthquake in New Zealand caused considerable structural damage. It is believed that this event has now resulted in demolition of about 65-70% of the building stock in the Central Business District (CBD), significantly crippling economic activities in the city of Christchurch. A major concern raised from this event was adequacy of the current seismic design practice adopted for reinforced concrete walls due to their poor performance in modern buildings. The relatively short-duration earthquake motion implied that the observed wall damage occurred in a brittle manner despite adopting a ductile design philosophy. This paper presents the lessons learned from the observed wall damage in the context of current state of knowledge in the following areas: concentrating longitudinal reinforcement in wall end regions; determining wall thickness to prevent out-of-plane wall buckling; avoiding lap splices in plastic hinge zones; and quantifying minimum vertical reinforcement. http://www.2eceesistanbul.org/

Research Papers, Lincoln University

On 4 September 2010, a 7.1 magnitude earthquake struck near Darfield, 40 kilometres west of Christchurch, New Zealand. The quake caused significant damage to land and buildings nearby, with damage extending to Christchurch city. On 22 February 2011, a 6.3 magnitude earthquake struck Christchurch, causing extensive and significant damage across the city and with the loss of 185 lives. Years on from these events, occasional large aftershocks continue to shake the region. Two main entomological collections were situated within close proximity to the 2010/11 Canterbury earthquakes. The Lincoln University Entomology Research Collection, which is housed on the 5th floor of a 7 storey building, was 27.5 km from the 2010 Darfield earthquake epicentre. The Canterbury Museum Entomology Collection, which is housed in the basement of a multi-storeyed heritage building, was 10 km from the 2011 Christchurch earthquake epicentre. We discuss the impacts of the earthquakes on these collections, the causes of the damage to the specimens and facilities, and subsequent efforts that were made to prevent further damage in the event of future seismic events. We also discuss the wider need for preparedness against the risks posed by natural disasters and other catastrophic events.

Research papers, Victoria University of Wellington

Measurement of basement seismic resonance frequencies can elucidate shallow velocity structure, an important factor in earthquake hazard estimation. Ambient noise cross correlation, which is well-suited to studying shallow earth structure, is commonly used to analyze fundamental-mode Rayleigh waves and, increasingly, Love waves. Here we show via multicomponent ambient noise cross correlation that the basement resonance frequency in the Canterbury region of New Zealand can be straightforwardly determined based on the horizontal to vertical amplitude ratio (H/V ratio) of the first higher-mode Rayleigh waves. At periods of 1-3 s, the first higher-mode is evident on the radial-radial cross-correlation functions but almost absent in the vertical-vertical cross-correlation functions, implying longitudinal motion and a high H/V ratio. A one-dimensional regional velocity model incorporating a ~ 1.5 km-thick sedimentary layer fits both the observed H/V ratio and Rayleigh wave group velocity. Similar analysis may enable resonance characteristics of other sedimentary basins to be determined. © 2013. American Geophysical Union. All Rights Reserved.