Our poster will present on-going QuakeCoRE-founded work on strong motion seismology for Dunedin-Mosgiel area, focusing on ground motion simulations for Dunedin Central Business District (CBD). Source modelling and ground motion simulations are being carried out using the SCEC (Southern California Earthquakes Center) Broad Band simulation Platform (BBP). The platform computes broadband (0-10 Hz) seismograms for earthquakes and was first implemented at the University of Otago in 2016. As large earthquakes has not been experienced in Dunedin in the time of period of instrumental recording, user-specified scenario simulations are of great value. The Akatore Fault, the most active fault in Otago and closest major fault to Dunedin, is the source focused on in the present study. Simulations for various Akatore Fault source scenarios are run and presented. Path and site effects are key components considered in the simulation process. A 1D shear wave velocity profile is required by SCEC BBP, and this is being generated to represent the Akatore-to-CBD path and site within the BBP. A 3D shear velocity model, with high resolution within Dunedin CBD, is being developed in parallel with this study (see Sangster et al. poster). This model will be the basis for developing a 3D shear wave velocity model for greater Dunedin-Mosgiel area for future ground motion simulations, using Canterbury software (currently under development).
The city of Christchurch and its surrounds experienced widespread damage due to soil liquefaction induced by seismic shaking during the Canterbury earthquake sequence that began in September 2010 with the Mw7.1 Darfield earthquake. Prior to the start of this sequence, the city had a large network of strong motion stations (SMSs) installed, which were able to record a vast database of strong ground motions. This paper uses this database of strong ground motion recordings, observations of liquefaction manifestation at the ground surface, and data from a recently completed extensive geotechnical site investigation program at each SMS to assess a range of liquefaction evaluation procedures at the four SMSs in the Christchurch Central Business District (CBD). In general, the characteristics of the accelerograms recorded at each SMS correlated well with the liquefaction evaluation procedures, with low liquefaction factors of safety predicted at sites with clear liquefaction identifiers in the ground motions. However, at sites that likely liquefied at depth (as indicated by evaluation procedures and/or inferred from the characteristics of the recorded surface accelerograms), the presence of a non-liquefiable crust layer at many of the SMS locations prevented the manifestation of any surface effects. Because of this, there was not a good correlation between surface manifestation and two surface manifestation indices, the Liquefaction Potential Index (LPI) and the Liquefaction Severity Number (LSN).
A photograph of the Cranmer Centre. Below a collection of masonry has been removed from the Cranmer Centre and placed on the ground.
An abandoned residential property at 16 Seabreeze Close in Bexley. Weeds are growing through the cracks in the ground and a window has been vandalised with graffiti.
An abandoned residential property at 18 Seabreeze Close in Bexley. Weeds are growing through the cracks in the ground and the yard has become overgrown.
A photograph of a large crack along the edge of a footpath near the Kaiapoi River. The ground has slumped, taking the fence posts with it.
A photograph of a large crack along the edge of a footpath near the Kaiapoi River. The ground has slumped, taking the fence posts with it.
A photograph of a large crack along the edge of a footpath near the Kaiapoi River. The ground has slumped, taking the fence posts with it.
A close-up photograph of part of the forecourt of a petrol station near New Brighton which has risen out of the ground and through the pavement.
A photograph of the former Government Life building in Cathedral Square. Shop windows on the ground level have been boarded up with plywood.
A photograph of University of Canterbury Geology students using ground penetrating radar equipment to survey land on the Greendale fault line. From left: Matt Cockcroft, Zach Whitman and Dewiyani Bealing.
A photograph of University of Canterbury Geology students using ground penetrating radar equipment to survey land on the Greendale fault line. From left: Matt Cockcroft, Zach Whitman and Dewiyani Bealing.
Hundreds of engineers are on the ground in Christchurch, assessing the damage in the wake of Tuesday's earthquake and are heading into the CBD en masse for the first time.
Two separate chances to inspect the Canterbury Television building were missed before the February earthquake saw it pancake to the ground last year, killing 115 people.
Liquefaction 'volcanos' in Kaiapoi, after the September 4th earthquake. Silt erupted out of the ground, piling up over the surface and leaving cracks at the mouth of the volcano.
Bare patches of ground at Sullivan Park in Avonside. The bare patches mark where liquefaction covered the grass after the 4 September 2010 earthquake.
A photograph of the interior of the Hotel Grand Chancellor. The photograph is captioned by BeckerFraserPhotos, "The ground floor of the Hotel Grand Chancellor".
A photograph captioned by BeckerFraserPhotos, "Ground floor of the Holiday Inn. We could see piles of different types of materials sorted and bagged through the windows here".
The east side of the Odeon Theatre, showing the severe damage at the back of the theatre. Part of the roof sits on the ground in the section next door.
A photograph of the earthquake damage to a house in Christchurch. The outer-side wall has crumbled, the bricks spilling onto the ground and buckling the fence.
The destruction of the Ground Culinary Centre on London Street. A digger is sitting on top of a pile of rubble. This site will soon be made into the Lyttelton Petanque Club.
The back entrance to the Ng art gallery building on Madras Street. The awning from Bains of Madras Street sits on the ground beside cordon fencing around a damaged building.
Liquefaction 'volcanos' in Kaiapoi, after the September 4th earthquake. Silt erupted out of the ground, piling up over the surface and leaving cracks at the mouth of the volcano.
Liquefaction 'volcanos' in Kaiapoi, after the September 4th earthquake. Silt erupted out of the ground, piling up over the turf and leaving cracks at the mouth of the volcano.
Liquefaction 'volcanos' in Kaiapoi, after the September 4th earthquake. Silt erupted out of the ground, piling up over the surface and leaving cracks at the mouth of the volcano.
Liquefaction 'volcanos' in Kaiapoi, after the September 4th earthquake. Silt erupted out of the ground, piling up over the surface and leaving cracks at the mouth of the volcano.
Liquefaction 'volcanos' in Kaiapoi, after the September 4th earthquake. Silt erupted out of the ground, piling up over the surface and leaving cracks at the mouth of the volcano.
Looking through the fence of a construction site where some ground foundation has been laid down. The heading on the sign on the fence says 'Caution. Construction Site. Authorised Personnel Only'.
A photograph of a large crack along the edge of a footpath near the Kaiapoi River. The ground has slumped, taking the fence posts with it.
Liquefaction 'volcanos' in Kaiapoi, after the September 4th earthquake. Silt erupted out of the ground, piling up over the surface and leaving cracks at the mouth of the volcano.