Liquefaction at Kaiapoi in the 1901 Cheviot, New Zealand, earthquake

Technical abstract

A clear case of seismic liquefaction occurred in northeast Kaiapoi during the 1901 Cheviot earthquake. A contemporary newspaper report describes the ejection of sand and lateral spreading in Waites' market garden at the east end of Sewell Street, Kaiapoi and also south of the Waimakariri River near Belfast.

Soil conditions at Waites' property in Sewell Street and at three other sites in northeast Kaiapoi were investigated by piezocone probing and rotary drilling. Loose, fine sands and silty sands, with a cone resistance qc as low as 2 to 3 Mpa, were found. These soils would be quite susceptible to liquefaction, and it is not surprising that they liquefied in 1901.

Lack of precise seismological parameters for the 1901 earthquake precludes any definite conclusions about the performance of liquefaction potential models.

A comparison of Dutch cone penetrometer resistances and standard penetration test N-values supports the old qc (bars)/N = 4 rule, but the data are quite scattered. In view of the large amount of scatter, use of the more refined rule of Robertson of Campanella, where qc/N is a function of D50, does not seem warranted.

Although the field results cannot be used with any precision to verify or recalibrate liquefaction models, they do confirm that there is a significant risk of liquefaction at Kaiapoi. Furthermore, we now have four reference sites, each with slightly different soil conditions, whose performance can be monitored following future earthquakes in the region.