Surface rupture of the Greendale Fault during the Darfield (Canterbury) earthquake, New Zealand

Abstract

The Mw 7.1 Darfield (Canterbury) earthquake of 4 September 2010 (NZST) was the first earthquake in New Zealand to produce ground-surface fault rupture since the 1987 Edgecumbe earthquake. Surface rupture of the previously unrecognised Greendale Fault during the Darfield earthquake extends for at least 29.5 km and comprises an en echelon series of east-west striking, left-stepping traces. Displacement is predominantly dextral strike-slip, averaging ~2.5 m, with maxima of ~5 m along the central part of the rupture. Maximum vertical displacement is ~1.5 m, but generally < 0.75 m. The south side of the fault has been uplifted relative to the north for ~80% of the rupture length, except at the eastern end where the north side is up. The zone of surface rupture deformation ranges in width from ~30 to 300 m, and comprises discrete shears, localised bulges and, primarily, horizontal dextral flexure. At least a dozen buildings were affected by surface rupture, but none collapsed, largely because most of the buildings were relatively flexible and robust timber-framed structures and because deformation was distributed over tens to hundreds of metres width. Many linear features, such as roads, fences, power lines, and irrigation ditches were offset or deformed by fault rupture, providing markers for accurate determinations of displacement.

Slip in the 2010–2011 Canterbury earthquakes, New Zealand

“…The authors called this newly recognized fault the Greendale Fault. The westernmost ∼5 km of the rupture trends WNW–ESE, approximately following the course of the Hororata river and in one place partially blocking its channel, leading to minor flooding of adjacent fields [ Quigley et al , 2010, Figure 5]. However, this westernmost part lacks coverage of Worldview imagery, aerial photography or LiDAR topography.…”

“…The faults that ruptured in the 2010 and 2011 earthquakes were previously unknown. Preliminary studies have already either mapped the surface ruptures [ Quigley et al , 2010], geodetically constrained the main fault segments [ Beavan et al , 2010] or determined the distribution of aftershocks [ Gledhill et al , 2011]. We combine Interferometric Synthetic Aperture Radar (InSAR) observations (Figure 2), with field mapping, aerial and satellite imagery, a post‐earthquake LiDAR Digital Elevation Model (DEM) and seismological body‐wave solutions to examine the distribution of rupture, and to model the locations and orientations of these previously unknown faults.…”

High‐resolution relocation of aftershocks of the Mw 7.1 Darfield, New Zealand, earthquake and implications for fault activity

“…Map showing seismic stations used in this study (triangles), the mapped surface rupture of the Greendale Fault (red line) [ Quigley et al ., ], and the epicenters of the Darfield and Christchurch earthquakes (solid stars). The approximate locations of the 1869 M w 4.7–4.9 Christchurch earthquake and the 1870 M w 5.6–5.8 Lake Ellesmere earthquake are shown by the outlined stars [ Downes and Yetton , ].…”

Faulting in Banks Peninsula: tectonic setting and structural controls for late Miocene intraplate volcanism, New Zealand

“…This late Cretaceous fault is probably dipping at about 60° to the south, whereas the largely dextral Greendale Fault is subvertical with a south-side-up component of movement (Quigley et al 2011). Similar cases where the strike of a new fault has been inherited from older structures but the dip has not have been reported by Ring (1994) from the East African Rift.…”

“…The ENE-WSW-striking faults also occur in the Lyttelton Harbour area and are considered to be either rotated late Cretaceous east-west faults or faults that formed in the late Miocene when the encroaching Chatham Rise interacted with the developing plate boundary zone on the South and North Island of New Zealand. Quigley et al (2011) and other faults with inferred kinematic axes are from Sibson et al (2012). Also shown are main faults in Banks Peninsula with kinematic axes inferred from the data presented in Figures 4-12. Because the method used for constructing principal shortening and extension axes for a given population of faults is similar to that used to determine infinitesimal strain directions for earthquake focal mechanisms (P-and T-axes, respectively), the kinematic axes can be compared.…”