Liquefaction features and the geologic environment in which they formed were carefully studied at two sites near Lincoln in southwest Christchurch. We undertook geomorphic mapping, excavated trenches, and obtained hand cores in areas with surficial evidence for liquefaction and areas where no surficial evidence for liquefaction was present at two sites (Hardwick and Marchand). The liquefaction features identified include (1) sand blows (singular and aligned along linear fissures), (2) blisters or injections of subhorizontal dikes into the topsoil, (3) dikes related to the blows and blisters, and (4) a collapse structure. The spatial distribution of these surface liquefaction features correlates strongly with the ridges of scroll bars in meander settings. In addition, we discovered paleoliquefaction features, including several dikes and a sand blow, in excavations at the sites of modern liquefaction. The paleoliquefaction event at the Hardwick site is dated at A.D. 908-1336, and the one at the Marchand site is dated at A.D. 1017-1840 (95% confidence intervals of probability density functions obtained by Bayesian analysis). If both events are the same, given proximity of the sites, the time of the event is A.D. 1019-1337. If they are not, the one at the Marchand site could have been much younger. Taking into account a preliminary liquefaction-triggering threshold of equivalent peak ground acceleration for an Mw 7.5 event (PGA7:5) of 0:07g, existing magnitude-bounded relations for paleoliquefaction, and the timing of the paleoearthquakes and the potential PGA7:5 estimated for regional faults, we propose that the Porters Pass fault, Alpine fault, or the subduction zone faults are the most likely sources that could have triggered liquefaction at the study sites. There are other nearby regional faults that may have been the source, but there is no paleoseismic data with which to make the temporal link.
Under the caption, young people carrying their baggage flutter into the air, away from Canterbury and toward 'Oz'. In September GNS Earth Sciences reported that after the earthquakes, the Greendale and associated faults were still moving as they settled into a new configuration. At the same time the young were leaving Canterbury (and New Zealand) for a better future in Australia. The population of New Zealand was moving into a new configuration. Quantity: 1 digital cartoon(s).
This paper develops representative ground motion ensembles for several major earthquake scenarios in New Zealand. Cases considered include representative ground motions for the occurrence of Alpine, Hope, and Porters Pass earthquakes in Christchurch, and the occurrence of Wellington, Wairarapa, and Ohariu, fault ruptures in Wellington. Challenges in the development of ground motion ensembles for subduction zone earthquakes are also highlighted. The ground motions are selected based on the generalized conditional intensity measure (GCIM) approach, ensuring that the ground motion ensembles represent both the mean, and distribution of ground motion intensity which such scenarios could impose. These scenario-based ground motion sets can be used to complement ground motions which are often selected in conjunction with probabilistic seismic hazard analysis, in order to understand the performance of structures for the question “what if this fault ruptures?”
An interview with Mark Quigley, lecturer in Active Tectonics/Tectonic Geomorphology at the University of Canterbury, about his experiences during the 22 February 2011 earthquake, and the active fault lines which caused the earthquakes. This video is part of The Press's 'Christchurch, one year after February 22, 2011' series.
Slipping of the tectonic plates caused tension cracks on this previously unknown faultline that runs through this paddock; magnitude 7.1 earthquake in mid-Canterbury on Saturday 4 September 2010.
Slipping of the tectonic plates caused tension cracks on this previously unknown faultline that runs through this paddock; magnitude 7.1 earthquake in mid-Canterbury on Saturday 4 September 2010.
This originally straight farm fence has been laterally displaced at least 2 metres where it crosses the previously unknown faultline from which the Saturday 4 September 2010 earthquake originated.
This originally straight farm fence has been laterally displaced at least 2 metres where it crosses the previously unknown Greendale Faultline from which the Saturday 4 September 2010 earthquake originated.
The faultline cuts across Telegraph Road, leaving a kink in its originally straight alignment; aftermath of the magnitude 7.1 earthquake in mid-Canterbury on Saturday 4 September 2010.
Slipping of the tectonic plates caused tension cracks on this previously unknown faultline that runs through this paddock; magnitude 7.1 earthquake in mid-Canterbury on Saturday 4 September 2010.
This originally straight farm fence has been laterally displaced at least 2 metres where it crosses the previously unknown faultline from which the Saturday 4 September 2010 earthquake originated.
This originally straight farm fence has been laterally displaced at least 2 metres where it crosses the previously unknown faultline from which the Saturday 4 September 2010 earthquake originated.
The faultline cuts across Telegraph Road, leaving a kink in its originally straight alignment; aftermath of the magnitude 7.1 earthquake in mid-Canterbury on Saturday 4 September 2010.
Slipping of the tectonic plates caused tension cracks on this previously unknown faultline that runs through this paddock; magnitude 7.1 earthquake in mid-Canterbury on Saturday 4 September 2010.
Slipping of the tectonic plates caused tension cracks on this previously unknown faultline that runs through this paddock; magnitude 7.1 earthquake in mid-Canterbury on Saturday 4 September 2010.
This originally straight farm fence has been laterally displaced at least 2 metres where it crosses the previously unknown faultline from which the Saturday 4 September 2010 earthquake originated.
This originally straight farm fence has been laterally displaced at least 2 metres where it crosses the previously unknown faultline from which the Saturday 4 September 2010 earthquake originated.
The faultline cuts across Telegraph Road, leaving a kink in its originally straight alignment; aftermath of the magnitude 7.1 earthquake in mid-Canterbury on Saturday 4 September 2010.
The faultline cuts across Telegraph Road, leaving a kink in its originally straight alignment; aftermath of the magnitude 7.1 earthquake in mid-Canterbury on Saturday 4 September 2010.
Slipping of the tectonic plates caused tension cracks on this previously unknown faultline that runs through this paddock; magnitude 7.1 earthquake in mid-Canterbury on Saturday 4 September 2010.
Slipping of the tectonic plates caused tension cracks on this previously unknown faultline that runs through this paddock; magnitude 7.1 earthquake in mid-Canterbury on Saturday 4 September 2010.
This originally straight farm fence has been laterally displaced at least 2 metres where it crosses the previously unknown faultline from which the Saturday 4 September 2010 earthquake originated.
This originally straight farm fence has been laterally displaced at least 2 metres where it crosses the previously unknown faultline from which the Saturday 4 September 2010 earthquake originated.
Slipping of the tectonic plates caused tension cracks on this previously unknown faultline that runs through this paddock; magnitude 7.1 earthquake in mid-Canterbury on Saturday 4 September 2010.
Slipping of the tectonic plates caused tension cracks on this previously unknown faultline that runs through this paddock; magnitude 7.1 earthquake in mid-Canterbury on Saturday 4 September 2010.
This originally straight farm fence has been laterally displaced at least 3 metres where it crosses the previously unknown faultline from which the Saturday 4 September 2010 earthquake originated.
Slipping of the tectonic plates caused tension cracks on this previously unknown faultline that runs through this paddock; magnitude 7.1 earthquake in mid-Canterbury on Saturday 4 September 2010.
This originally straight farm fence has been laterally displaced at least 2 metres where it crosses the previously unknown faultline from which the Saturday 4 September 2010 earthquake originated.
Slipping of the tectonic plates caused tension cracks on this previously unknown faultline that runs through this paddock; magnitude 7.1 earthquake in mid-Canterbury on Saturday 4 September 2010.
Slipping of the tectonic plates caused tension cracks on this previously unknown faultline that runs through this paddock; magnitude 7.1 earthquake in mid-Canterbury on Saturday 4 September 2010.