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An overview of the 22 February 2011 Christchurch earthquake is presented in the context of characterization of extreme/rare events. Focus is given to the earthquake source, observed near-source strong ground motions, and effects of site response, while structural response and consequences are mentioned for completeness. For each of the above topics comparisons and discussions are made with predictive models for each of phenomena considered. In light of the observations and predictive model comparisons, the author’s opinion on improving the characterization of such extreme/rare events, and their appropriate consideration in seismic design is presented
This poster provides a comparison between the strong ground motions observed in the 22 February 2011 Mw6.3 Christchurch earthquake with those observed in Tokyo during the 11 March 2011 Mw9.0 Tohoku earthquake. The destuction resulting from both of these events has been well documented, although tsunami was the principal cause of damage in the latter event, and less attention has been devoted to the impact of earthquake-induced ground motions. Despite Tokyo being located over 100km from the nearest part of the causative rupture, the ground motions observed from the Tohoku earthquake were significant enough to cause structural damage and also significant liquefaction to loose reclaimed soils in Tokyo Bay. The author was fortunate enough (from the perspective of an earthquake engineer) to experience first-hand both of these events. Following the Tohoku event, the athor conducted various ground motion analyses and reconniassance of the Urayasu region in Tokyo Bay affected by liquefaction in collaboration with Prof. Kenji Ishihara. This conference is therefore a fitting opportunity in which to discuss some of authors insights obtained as a result of this first hand knowledge. Figure 1 illustrates the ground motions recorded in the Christchurch CBD in the 22 February 2011 and 4 September 2010 earthquakes, with that recorded in Tokyo Bay in the 11 March 2011 Tohoku earthquake. It is evident that these three ground motions vary widely in their amplitude and duration. The CBGS ground motion from the 22 February 2011 event has a very large amplitude (nearly 0.6g) and short duration (approx. 10s of intense shaking), as a result of the causal Mw6.3 rupture at short distance (Rrup=4km). The CBGS ground motion from the 4 September 2010 earthquake has a longer duration (approx. 30s of intense shaking), but reduced acceleration amplitude, as a result of the causal Mw7.1 rupture at a short-to-moderate distance (Rrup=14km). Finally, the Urayasu ground motion in Tokyo bay during the 11 March 2011 Tohoku earthquake exhibits an acceleration amplitude similar to the 4 September 2010 CBGS ground motion, but a significantly larger duration (approx 150s of intense shaking). Clearly, these three different ground motions will affect structures and soils in different ways depending on the vibration characteristics of the structures/soil, and the potential for strength and stiffness degradation due to cumulative effects. Figure 2 provides a comparison between the arias intensities of the several ground motion records from the three different events. It can be seen that the arias intensities of the ground motions in the Christchurch CBD from the 22 February 2011 earthquake (which is on average AI=2.5m/s) is approximately twice that from the 4 September 2010 earthquake (average AI≈1.25). This is consistent with a factor of approximately 1.6 obtained by Cubrinovski et al. (2011) using the stress-based (i.e.PGA-MSF) approach of liquefaction triggering. It can also be seen that the arias intensity of the ground motions recorded in Tokyo during the 2011 Tohoku earthquake are larger than ground motions in the Christchurch CBD from the 4 September 2011 earthquake, but smaller than those of the 22 February 2011 earthquake. Based on the arias intensity liquefaction triggering approach it can therefore be concluded that the ground motion severity, in terms of liquefaction potential, for the Tokyo ground motions is between those ground motions in Christchurch CBD from the 4 September 2010 and 22 February 2011 events.
Text at top reads 'Some Christchurch suburbs to move?... The cartoon shows three complete suburbs that have been dug up and are now being flown by helicopters attached to tall towers to their new spots on the Australian Gold Coast. Someone in one of the houses on the move yells 'Woohoo! Yeehaa! Well... As NZ and Ozzie are such great mates... Gold Coast here we come!' Context - In some cases where whole communities have to move because the earthquakes have made it impossible for them to remain in their present locations, many in the community have elected to try to move and relocate together in order to retain their old neighbours and community spirit. Quantity: 1 digital cartoon(s).
Anyone keeping a global tally of recent disasters is likely to be asking: What role will the hazards and disasters of coastal plains play in the lives and economies of 21st century humanity? In this article, we reflect on this question using examples of how different types of coastal land performed during the Christchurch and other earthquake events to examine the complex of coastal-tectonic hazards that are being constructed in the Tokyo megacity
"There are major faults in low-seismicity areas that could produce a major event."
The Taiwanese Search and Rescue team being farewelled at the Christchurch International Airport after helping out with the emergency response to the Canterbury Earthquake.
The Taiwanese Search and Rescue team being farewelled at the Christchurch International Airport after helping out with the emergency response to the Canterbury Earthquake.
The Taiwanese Search and Rescue team being farewelled at the Christchurch International Airport after helping out with the emergency response to the Canterbury Earthquake.
New research shows the Canterbury earthquakes generated eight million tonnes of waste - forty times what would normally come from local households in a year.
It was just a little under an hour and a half ago, two years today, that a seven-point-one magnitude earthquake shook Canterbury.
Some Canterbury homeowners say their houses are dropping in value because of misleading estimates of damage to foundations from the 2010 and 2011 earthquakes.
West Auckland residents begin the cleanup after yesterday's tornado. The Canterbury Earthquakes Royal Commission calls for the seismic grading of all non-residential buildings.
Businesses appear to be getting over the shock of the February earthquake in Canterbury with many more now saying they expect better times ahead.
Despite taking a 200-thousand dollar pay cut, the new head of the Canterbury Earthquake Recovery Authority says he's delighted to have the job.
Later today at 12.51 many parts of the country will be stopping for two minutes silence for the victims of the Canterbury earthquake.
Fletcher Construction has won the largest building contract in New Zealand history to repair half of the Canterbury homes damaged in last month's earthquake.
Witnesses before the Canterbury Earthquake Royal Commission have been questioned over whether preservation of heritage buildings was given more consideration than preserving human lives.
Canterbury retail spending surges following earthquake disruptions. Traders face potential prison terms in Britain's rate-rigging scandal and the sharemarket falls half a percent.
A freshwater biologist says a tsunami of sediment and sand caused by the Canterbury earthquakes is choking the city's riverbeds and killing aquatic life.
The Taiwanese Search and Rescue team being farewelled at the Christchurch International Airport after helping out with the emergency response to the Canterbury Earthquake.
The Christchurch couple told they can't use part of their property because the Canterbury Earthquake Recovery Authority (CERA) might need access to it.
What's being called a landmark settlement with the Earthquake Commission has been reached today, which may have far-reaching consequences for Canterbury home-owners.
Photograph captioned by Fairfax, "Canterbury earthquake. Viv Montgomerie and Rick Garner with Gabrielle Montgomerie (front) 18 who sheltered in the doorway for 2 hours".
Photograph captioned by Fairfax, "Canterbury earthquake. People look at what was once a straight section of Telegraph Road that moved sideways by 3 metres".
A photograph of street art at the Addington Saleyards, taken before the Canterbury earthquakes. One of the art works depicts an intoxicated Mickey Mouse.
Photograph captioned by Fairfax, "Two months after the Canterbury Earthquake Manchester Street between Gloucester and Hereford Streets is still a way from being sorted".
Lyttelton Port is applauding a government decision to use the Canterbury Earthquake Recovery Act to speed up the redevelopment of the badly damaged port.
The Taiwanese Search and Rescue team being farewelled at the Christchurch International Airport after helping out with the emergency response to the Canterbury Earthquake.