First seismic imaging results of tectonically complex structures at shallow depths beneath the northwest Canterbury Plains, New Zealand

Dorn, Caroline; Carpentier, S.; Kaiser, Anna; Green, A.G.; Horstmeyer, Heinrich; Campbell, Fiona; Campbell, J.; Jongens, Richard; Finnemore, M.; Nobes, David C.

doi:10.1016/j.jappgeo.2009.06.003

Cited by 13 publications

(25 citation statements)

References 26 publications

(22 reference statements)

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“…A 240 channel seismic recording system with single 30 Hz geophones spaced at 5 m intervals and explosive/ hammer sources every 10/5 m yielded nominal 30/120-fold data with 2.5 m subsurface sampling. A data-adaptive processing scheme that included time-and space-variant spectral balancing, custom static corrections and mutes, frequencydistance (F-X) deconvolution, dip-moveout (DMO) corrections, and finite difference time migration [Yilmaz, 2001] was Further details on the data acquisition strategy are provided by Dorn et al [2010]. Because it was inappropriate to detonate explosions within the town of Sheffield, a hammer source was used at x = 6.8 to 8.3 km along seismic line S2 (see Figures 6c and 6f).…”

Section: Seismic Reflection Data Acquisition and Processingmentioning

confidence: 99%

“…AGC, automatic gain control; DMO, dip-moveout; FD, finite difference; F-X, frequency-space; NMO normal-moveout; CVS, constantvelocity stacks. The principles of these processes are described by Yilmaz [2001], and their application to the Canterbury Plains data is outlined by Dorn et al [2010]. gently dipping, to undulating reflection unit Qo, which is only seen northwest of x ≈ 6.0 km and southeast of x ≈ 12.0 km.…”

Section: Significant Reflection Packages and Low-reflectivity Regionsmentioning

confidence: 99%

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High‐resolution seismic images of potentially seismogenic structures beneath the northwest Canterbury Plains, New Zealand

Dorn¹,

Green²,

Jongens³

et al. 2010

J. Geophys. Res.

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[1] The transpressional boundary between the Australian and Pacific plates in the central South Island of New Zealand comprises the Alpine Fault and a broad region of distributed strain concentrated in the Southern Alps but encompassing regions further to the east, including the northwest Canterbury Plains. Low to moderate levels of seismicity (e.g., 2 > M 5 events since 1974 and 2 > M 4.0 in 2009) and Holocene sediments offset or disrupted along rare exposed active fault segments are evidence for ongoing tectonism in the northwest plains, the surface topography of which is remarkably flat and even. Because the geology underlying the late Quaternary alluvial fan deposits that carpet most of the plains is not established, the detailed tectonic evolution of this region and the potential for larger earthquakes is only poorly understood. To address these issues, we have processed and interpreted high-resolution (2.5 m subsurface sampling interval) seismic data acquired along lines strategically located relative to extensive rock exposures to the north, west, and southwest and rare exposures to the east. Geological information provided by these rock exposures offer important constraints on the interpretation of the seismic data. The processed seismic reflection sections image a variably thick layer of generally undisturbed younger (i.e., < 24 ka) Quaternary alluvial sediments unconformably overlying an older (>59 ka) Quaternary sedimentary sequence that shows evidence of moderate faulting and folding during and subsequent to deposition. These Quaternary units are in unconformable contact with Late Cretaceous-Tertiary interbedded sedimentary and volcanic rocks that are highly faulted, folded, and tilted. The lowest imaged unit is largely reflection-free PermianTriassic basement rocks. Quaternary-age deformation has affected all the rocks underlying the younger alluvial sediments, and there is evidence for ongoing deformation. Eight primary and numerous secondary faults as well as a major anticlinal fold are revealed on the seismic sections. Folded sedimentary and volcanic units are observed in the hanging walls and footwalls of most faults. Five of the primary faults represent plausible extensions of mapped faults, three of which are active. The major anticlinal fold is the probable continuation of known active structure. A magnitude 7.1 earthquake occurred on 4 September 2010 near the southeastern edge of our study area. This predominantly right-lateral strike-slip event and numerous aftershocks (ten with magnitudes ≥5 within one week of the main event) highlight the primary message of our paper: that the generally flat and topographically featureless Canterbury Plains is underlain by a network of active faults that have the potential to generate significant earthquakes.

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Section: Seismic Reflection Data Acquisition and Processingmentioning

confidence: 99%

Section: Significant Reflection Packages and Low-reflectivity Regionsmentioning

confidence: 99%

High‐resolution seismic images of potentially seismogenic structures beneath the northwest Canterbury Plains, New Zealand

Dorn¹,

Green²,

Jongens³

et al. 2010

J. Geophys. Res.

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“…1c with the goal of mapping the faults and folds underlying the northwest Canterbury Plains Dorn et al (2009Dorn et al ( , 2010. We also took advantage of the four short seismic reflection lines M1-M4 acquired by Finnemore (2004) and the northern end of the industry seismic reflection line IPE4 described by Jongens et al (1999).…”

Section: Introductionmentioning

confidence: 99%

“…4; Dorn et al, 2009Dorn et al, , 2010; poor resolution in the uppermost~20 m is a consequence of source-generated noise (Robertsson et al, 1996) and generally reduced fold (i.e., subsurface coverage). Hints of seismic reflections as shallow~10 m are present in the images of Fig.…”

Section: Introductionmentioning

confidence: 99%

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Recent deformation of Quaternary sediments as inferred from GPR images and shallow P-wave velocity tomograms: Northwest Canterbury Plains, New Zealand

Carpentier

Green

Doetsch

et al. 2012

Journal of Applied Geophysics

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

et al. 2013

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Low‐slip‐rate regions often represent under‐recognized hazards, and understanding the progression of seismicity when faults in such areas rupture will help us to better understand earthquake rupture patterns. The 3 September 2010 (UTC) Mw 7.1 Darfield earthquake revealed a formerly unrecognized set of faults in the Canterbury region of New Zealand, an area that had previously been mapped as one of the lower‐hazard areas in the country. In this study, we analyze the first four months of its aftershock sequence to identify active faults and temporal changes in seismicity along them. We jointly invert for three‐dimensional P wave and S wave velocities and hypocentral locations, using data for 2840 aftershocks recorded at 36 temporary and permanent seismic stations within 70 km of the main shock epicenter. These relocations delineate eight individual faults active prior to the 22 February 2011 Mw 6.3 Christchurch earthquake, the largest aftershock of the Darfield earthquake. Two of these faults are in the Christchurch region, one of which corresponds to geodetically determined rupture planes of the Christchurch earthquake. Using focal mechanisms calculated from first‐motion polarities, we find mainly strike‐slip faulting events, with some reverse and normal faulting events as well. We compare the orientations of these faults to the prevailing regional stress directions to identify which faults may have been active prior to the Darfield earthquake and which may be newly developed.

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First seismic imaging results of tectonically complex structures at shallow depths beneath the northwest Canterbury Plains, New Zealand

Cited by 13 publications

References 26 publications

High‐resolution seismic images of potentially seismogenic structures beneath the northwest Canterbury Plains, New Zealand

High‐resolution seismic images of potentially seismogenic structures beneath the northwest Canterbury Plains, New Zealand

Recent deformation of Quaternary sediments as inferred from GPR images and shallow P-wave velocity tomograms: Northwest Canterbury Plains, New Zealand

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

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First seismic imaging results of tectonically complex structures at shallow depths beneath the northwest Canterbury Plains, New Zealand

Cited by 13 publications

References 26 publications

High‐resolution seismic images of potentially seismogenic structures beneath the northwest Canterbury Plains, New Zealand

High‐resolution seismic images of potentially seismogenic structures beneath the northwest Canterbury Plains, New Zealand

Recent deformation of Quaternary sediments as inferred from GPR images and shallow P-wave velocity tomograms: Northwest Canterbury Plains, New Zealand

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

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