Spatial variation of magnitude scaling factors during the 2010 Darfield and 2011 Christchurch, New Zealand, earthquakes

• Published in: Soil dynamics and earthquake engineering (1984) 2016-12, Vol.91, p.175-186
• Main Authors: Carter, W.L., Green, R.A., Bradley, B.A., Wotherspoon, L.M., Cubrinovski, M.
• Format: Article
• Language: English
• Subjects: Canterbury earthquakes; Christchurch; Computation; Earthquakes; Liquefaction; Magnitude scaling factors; Scaling; Scaling factors; Seismic activity; Seismic response; Seismology; Studies; Variation
• ISSN: 0267-7261; 1879-341X
• DOI: 10.1016/j.soildyn.2016.09.044

The combination of well-documented liquefaction response during the Darfield and Christchurch, New Zealand, earthquakes, densely-recorded ground motions for the events, and detailed subsurface characterization provides an unprecedented opportunity to investigate the significance of the spatial variation of magnitude scaling factors (MSF) on liquefaction triggering. Towards this end, MSF were computed at 15 SMS sites across Christchurch and its surroundings using two established approaches. Trends in the spatial variation of the MSF computed using number of equivalent cycles (neq) from both approaches were similar, with the spatial variation being more significant for the Christchurch earthquake than the Darfield earthquake. However, there was no consistent trend for regions with lower computed MSF having experienced more severe or widespread liquefaction. Additionally, there is a general correlation between MSF and amax, but because amax ranges more widely than MSF it has a greater influence on the resulting seismic demand imposed on the soil than MSF does. Nevertheless, the spatial variation of the MSF is deemed significant enough that it warrants being considered for incorporation into future variants of simplified liquefaction evaluation procedures. •This study investigates the spatial variation of magnitude scaling factors.•Two well-documented earthquakes in New Zealand were used to investigate the spatial variation of MSF.•A general trend was identified that MSF correlate with PGA.•From a seismic demand perspective, PGA is more influential on liquefaction triggering than MSF.