A team of earthquake geologists, seismologists and engineering seismologists from GNS Science, NIWA, University of Canterbury, and Victoria University of Wellington have collectively produced an update of the 2002 national probabilistic seismic hazard (PSH) model for New Zealand. The new model incorporates over 200 new onshore and offshore fault sources, and utilises newly developed New Zealand-based scaling relationships and methods for the parameterisation of the fault and subduction interface sources. The background seismicity model has also been updated to include new seismicity data, a new seismicity regionalisation, and improved methodology for calculation of the seismicity parameters. Background seismicity models allow for the occurrence of earthquakes away from the known fault sources, and are typically modelled as a grid of earthquake sources with rate parameters assigned from the historical seismicity catalogue. The Greendale Fault, which ruptured during the M7.1, 4 September 2010 Darfield earthquake, was unknown prior to the earthquake. However, the earthquake was to some extent accounted for in the PSH model. The maximum magnitude assumed in the background seismicity model for the area of the earthquake is 7.2 (larger than the Darfield event), but the location and geometry of the fault are not represented. Deaggregations of the PSH model for Christchurch at return periods of 500 years and above show that M7-7.5 fault and background source-derived earthquakes at distances less than 40 km are important contributors to the hazard. Therefore, earthquakes similar to the Darfield event feature prominently in the PSH model, even though the Greendale Fault was not an explicit model input.
Small, tight-knit communities, are complex to manage from outside during a disaster. The township of Lyttelton, New Zealand, and the communities of Corsair Bay, Cass Bay, and Rapaki to the east, are especially more so difficult due to the terrain that encloses them, which caused them to be cut-off from Christchurch, the largest city in the South Island, barely 10 km away, after the Mw 7.1 Darfield Earthquake and subsequent Canterbury Earthquake Sequence. Lyttelton has a very strong and deep-rooted community spirit that draws people to want to be a part of Lyttelton life. It is predominantly residential on the slopes, with retail space, service and light industry nestled near the harbour. It has heritage buildings stretching back to the very foundation of Canterbury yet hosts the largest, modern deep-water port for the region. This study contains two surveys: one circulated shortly before the Darfield Earthquake and one circulated in July 2011, after the Christchurch and Sumner Earthquakes. An analytical comparison of the participants’ household preparedness for disaster before the Darfield Earthquake and after the Christchurch and Sumner Earthquakes was performed. A population spatiotemporal distribution map was produced that shows the population in three-hourly increments over a week to inform exposure to vulnerability to natural hazards. The study went on to analyse the responses of the participants in the immediate period following the Chrsitchurch and Sumner Earthquakes, including their homeward and subsequent journeys, and the decision to evacuate or stay in their homes. Possible predictors to a decision to evacuate some or all members of the household were tested. The study also asked participants’ views on the events since September 2010 for analysis.
The ground literally opened up! On the previously unknown faultline along which the Saturday 4 September 2010 earthquake originated.
The ground literally opened up! On the previously unknown faultline along which the Saturday 4 September 2010 earthquake originated.
The ground literally opened up! On the previously unknown faultline along which the Saturday 4 September 2010 earthquake originated.
The ground literally opened up! On the previously unknown faultline along which the Saturday 4 September 2010 earthquake originated.
The 4 September 2010 Darfield and 22 February 2011 Christchurch earthquakes caused significant damage to Christchurch and surrounding suburbs as a result of the widespread liquefaction and lateral spreading that occurred. Ground surveying-based field investigations were conducted following these two events in order to measure permanent ground displacements in areas significantly affected by lateral spreading. Data was analysed with respect to the distribution of lateral spreading vs. distance from the waterway, and the failure patterns observed. Two types of failure distribution patterns were observed, a typical distributed pattern and an atypical block failure. Differences in lateral spreading measurements along adjacent banks of the Avon River in the area of Dallington were also examined. The spreading patterns between the adjacent banks varied with the respective river geometry and/or geotechnical conditions at the banks.
Photograph captioned by Fairfax, "New Zealand's Governor-General Anand Satyanand and his wife Susan Satyanand visited sites around earthquake-stricken Canterbury today. Satyanand at the epicentre near Darfield where the new fault line can be clearly seen across a rural paddock".
Photograph captioned by Fairfax, "Damage to St. Mary's Anglican Church Timaru resulting from 7.1 Magnitude Earthquake centred near Darfield. (L to R): Builder Kevin Deam and St. Mary's parishioner Craig Perkins inspect a damaged spire on the church tower".
Photograph captioned by Fairfax, "New Zealand's Governor-General Anand Satyanand and his wife Susan Satyanand visited sites around earthquake stricken Canterbury today. Satyanand at the epicentre near Darfield where the new fault line can be clearly seen across a rural paddock".
Photograph captioned by Fairfax, "New Zealand's Governor-General Anand Satyanand and his wife Susan Satyanand visited sites around earthquake stricken Canterbury today. Satyanand at the epicentre near Darfield where the new fault line can be clearly seen across a rural paddock".
Photograph captioned by Fairfax, "New Zealand's Governor-General Anand Satyanand and his wife Susan Satyanand visited sites around earthquake stricken Canterbury today. Satyanand at the epicentre near Darfield where the new fault line can be clearly seen across a rural paddock".
The 2010 Darfield earthquake is the largest earthquake on record to have occurred within 40 km of a major city and not cause any fatalities. In this paper the authors have reflected on their experiences in Christchurch following the earthquake with a view to what worked, what didn’t, and what lessons can be learned from this for the benefit of Australian earthquake preparedness. Owing to the fact that most of the observed building damage occurred in Unreinforced Masonry (URM) construction, this paper focuses in particular on the authors’ experience conducting rapid building damage assessment during the first 72 hours following the earthquake and more detailed examination of the performance of unreinforced masonry buildings with and without seismic retrofit interventions
At Greendale Faultline on Highfield Road in mid-Canterbury, where the magnitude 7.1 earthquake on 4 September 2010 originated.
Heaving and subsidence on the faultline left scars where the magnitude 7.1 earthquake on Saturday 4 September 2010 originated.
The latest (but temporary) tourist attraction in mid-Canterbury! This was the previously unknown faultline where the Saturday 4 September 2010 earthquake originated.
At Greendale Faultline on Highfield Road in mid-Canterbury, where the magnitude 7.1 earthquake on 4 September 2010 originated.
At Greendale Faultline on Highfield Road in mid-Canterbury, where the magnitude 7.1 earthquake on 4 September 2010 originated.
Tension cracks at least 300 mm deep, on the previously unknown faultline from which the Saturday 4 September 2010 earthquake originated.
Rolleston/Burnham, South Island, NZ This used to be a perfectly straight and flat road!
Photograph captioned by Fairfax, "Damage to St. Mary's Anglican Church Timaru resulting from 7.1 Magnitude Earthquake centred near Darfield. Damage can be seen to the spires on the church tower. The spire-tops were removed for safety and to be repaired".
Photograph captioned by Fairfax, "Damage to St. Mary's Anglican Church Timaru resulting from 7.1 Magnitude Earthquake centred near Darfield . (L to R): St. Mary's parishioner Craig Perkins and builder Kevin Deam secure the final damaged spire to be removed from the church tower".
The objective of this study is to examine the influence of near-fault motions on liquefaction triggering in Christchurch and neighboring towns during the 2010-2011 Canterbury earthquake sequence (CES). The CES began with the 4 September 2010, Mw7.1 Darfield earthquake and included up to ten events that triggered liquefaction. However, most notably, widespread liquefaction was induced by the Darfield earthquake and the Mw6.2, 22 February 2011 Christchurch earthquake. Of particular relevance to this study is the forward directivity effects that were prevalent in the motions recorded during the Darfield earthquake, and to a much lesser extent, during the Christchurch earthquake. A 2D variant of the Richart-Newmark fatigue theory was used to compute the equivalent number of cycles (neq) for the ground motions, where volumetric strain was used as the damage metric. This study is unique because it considers the contribution and phasing of both the fault-normal and fault-parallel components of motion on neq and the magnitude scaling factor (MSF). It was found that when the fault-normal and fault-parallel motions were treated individually, the former yielded a lower neq than the latter. Additionally, when the combined effects of fault-normal and fault-parallel components were considered, it was found that the MSF were higher than those commonly used. This implies that motions containing near-fault effects are less demanding on the soil than motions that do not. This may be one of several factors that resulted in less severe liquefaction occurring during the Darfield earthquake than the Christchurch earthquake.
Looking across the faultline where the Saturday 4 September 2010 magnitude 7.1 earthquake originated. Note how much the previously straight fence is now out of alignment.
Looking across the faultline where the Saturday 4 September 2010 magnitude 7.1 earthquake originated. Note how much the previously straight fence is now out of alignment.
Photograph captioned by Fairfax, "Damage to St. Mary's Anglican Church Timaru resulting from 7.1 Magnitude Earthquake centred near Darfield. The last damaged spire-top is removed from the church tower, secured to the crane by St. Mary's parishioner Craig Perkins (obscured) and builder Kevin Deam".
Photograph captioned by Fairfax, "Damage to St. Mary's Anglican Church Timaru resulting from 7.1 Magnitude Earthquake centred near Darfield . (L to R): Builder Kevin Deam and St. Mary's parishioner Craig Perkins are hoisted by crane to remove the last damaged spire from the church tower".
Photograph captioned by Fairfax, "Damage to St. Mary's Anglican Church Timaru resulting from 7.1 Magnitude Earthquake centred near Darfield. (L to R): Builder Kevin Deam and St. Mary's parishioner Craig Perkins are hoisted by crane to remove the last damaged spire from the church tower".
Photograph captioned by Fairfax, "Damage to St. Mary's Anglican Church Timaru resulting from 7.1 Magnitude Earthquake centred near Darfield . The final damaged spire is removed from the church tower by crane, secured by (L to R): St. Mary's parishioner Craig Perkins and builder Kevin Deam".
Photograph captioned by Fairfax, "Damage to St. Mary's Anglican Church Timaru resulting from 7.1 Magnitude Earthquake centred near Darfield. (L to R): Builder Kevin Deam and St. Mary's parishioner Craig Perkins are moved into position by crane to remove damaged spire-tops from the church tower".