Abstract
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. Piezocone probing and rotary drilling on the Waites property in Sewell Street and at three other sites in northeast Kaiapoi found loose, fine sands and silty sands with cone resistance 4: as low as 2 to 3 MPa; it is not surprising that liquefaction was observed in 1901. Lack of precise seismological parameters for the 1901 earthquake precludes any definite conclusions about the performance of liquefaction potential models. However, the occurrence of liquefaction strongly suggests that the M6.5 magnitude estimated by Dibble et al. [1980] is too small, and that local magnitude in 1901 was larger than the surface-wave value of about 6.9 of Dowrick and Smith [1990]. A value in the range of 7.1 to 7.5 seems more likely. Comparison of Dutch cone penetrometer resistances and standard penetration test N-values supports the old qc (bars)/N = 4 rule. Because 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 justified. The penetration testing results 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.
Highlights
The 1901 Cheviot earthquake is one of the strongest earthquakes to occur in the Canterbury province of the South Island of New Zealand since European settlement
Silty fine sands with cone resistances ranging from 2 to 5 MPa were found at all four sites
While it was not possible to pinpoint the 1901 sites precisely, the Sewell Street test site was almost certainly very close to, if not within, the Waites Market garden referred to in the 1901 newspaper reports and which was the principal site of liquefaction
Summary
The 1901 Cheviot earthquake is one of the strongest earthquakes to occur in the Canterbury province of the South Island of New Zealand since European settlement. It is clear that liquefaction occurred over an area of about two or three town blocks at the eastern end of Sewell and Charles Streets on the north bank of the Kaiapoi River (Figures 2, 4). One of the few vacant blocks of land in the original Waites market garden was found at 125 Sewell St, east of Jollie St. Dutch cone (CPTU) probes, using both Parez and Fugro piezecones, were carried out at this site and at three other sites east of Williams St and north of the Kaiapoi River (Figure 4). The first tests were made at the Sewell St site in 1986, using a 45 mm Parez cone [Ooi, 1987] They showed a layer of loose sand (qc :s; 5 MPa, Rr :s; 0.5%) between 2 to 6 m with a high liquefaction potential. There are fluctuations in qc, probably reflecting sublayers; but the fairly uniform and small value of Rr indicates that the material is predominantly
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